Dracaenas are sensitive to both Chlorine & Fluoride in tap water. That's most likely the reason for the tips of the leaves turning brown like that. You can try leaving some water sitting out for at least a day, giving the Chlorine time to evaporate away. I don't think that there's much you can do about the Fluoride tho, it can't evaporate.

Leaving the tap water sitting out for at least a day might work. For some people it does, but others it doesn't.
I tried this method out when I bought a couple of Dracaenas. It seemed to work fine at first, then one of them started showing signs of browning too, but only on a couple of leaves. Luckily, I was closely monitoring both plants and noticed it right away. So the browning was very small and only on the very tip of the leaves.

After I noticed it, I stopped watering them with tap water. I collect and store a lot of rainwater to use for my carnivorous plants, because you can't use tap water on them. So I have more than enough of it in my reserves, and now use it to water both of my Dracaenas as well. Since then, the browning hasn't gotten any worse.

If you don't want or have the spare time to collect rainwater, or don't live in an area where it rains that much, then you can buy distilled water fairly cheap at the store. But for me, collecting rainwater is the way to go. It's fairly easy, once you get the hang of it, and it doesn't take up a whole lot of time either. Plus, it's free. :)

If one is doing fine and the other not, I would question the roots integrity...

Most likely one suffered at the hands of the grower or store while the other is making it ok..Happens all the time. That is why I always lift them from the pot before bringing them home, especially for Dracanea and Palms..

Sometimes the root damage is iriversable and or can take time to correct themselves..

The water that Tommy mentioned is very true, and that is why I try to use only rain water on plants like this, but not your fault in this case since the other is fine at the moment by your methods..

I would see if you can return it for a healthier one or don't expect much from it while you properly care for it.

Check the roots, if they are white then I would flush that pot out with fresh water..
If they are rotted, the you know it was not your fault.

Good luck. Please let us know how it comes along.

Thank you for your replies.
I already use rainwater whenever I can and if I cant get it ( since it does'nt rain much in Georgia ) I always leave water out for three days at least before using it on my plants. Maybe I should just go ahead and buy bottled water.
The other Dracaena that I have was bought about two weeks after this one and it was in a very bad way which is why I brought it as I wanted to rescue it from the store! It is doing incredibly well with the same water and light. It is also potted with a pothos on the bottom. I don't know if that has anything to do with it doing well? Anyway, I thank you for your advice and rather than take it back to the store I will keep the big one and keep trying. Maybe you are right about the roots. Could it be because I just repotted it? maybe it needs time to readjust? Attached is a picture of the newer smaller one with the pothos , which was very yellow and brown when i got it but after clipping it seemed to settle as you can see.

Bottled drinking water is usually spring water, or just tap water from somewhere. Not to be nit-picky, but just want to make sure you don't waste money on this more expensive water vs. distilled.

At the store, plants were probably watered with tap water. The effects of that damage could take a while to pass. Dracs grow very slowly.

When you repotted, did you remove the old soil from the root ball?

The last pic looks awesome!!

Ok, so I think I have found what is wrong. How stupid of me! The big plant is by the same window as the smaller one, however it is much taller and is at the other side of the window. We have venetian blinds on that window, which are always closed so minimal light gets through, but at the top there is a smaller window which lets light in. After inspecting where the yellow leaves are, it is now clear that light is hitting those leaves. So I guess that's my problem. Too much light! The other one is doing so well because it doesnt get too much! I have put a shade up over the smaller window so that it gets light but minimal. I hope this helps. Should I take off the leaves that are yellow and brown? I'm guessing they won't go green again?
Kerry

Bottled water is tap water people "believe" is worth paying for. Always keep in mind that chlorine evaporates from water but fluoride does not, so if you can't secure enough rain water for your plants, you can let tap sit out, but it will still contain fluoride. I live in Oklahoma and also deal with dry summers and not enough rain water at times. I researched what plants are fluoride sensitive, and when my rain water reserves are running low, I save the rain water for my fluoride-sensitive plants and use chlorine-free tap for my plants that can tolerate it. I also have a lot of five-gallon buckets with lids that sit under my eaves so I can catch water year round and have a good supply. Even then I do run out.

Good luck!

Sitting will allow volatile forms of chlorine to evaporate but that's not the way all municipalities do it. If your tap is chlorinated with a non-volatile form, sitting will only concentrate it.

Kerry, great job considering possible variables, but the yellow in your first pic doesn't look like sunburn. From what I can see in these pics, there's not enough light to sunburn this plant. You're right, they can't turn green again, so removing them would make the plant more appealing-looking.

If changing to water without chlorine and fluoride in it doesn't help, there's likely an issue with the roots being able to function. The info here is excellent for helping plants to stay healthy.

If the old soil is still in the root ball, now surrounded by 'new' soil around the edges, there would likely be difficulty for water to move evenly between the 2 soils. There could also still be a lot of fluoride and/or chlorine in that old soil.

Dracaenas grow very slowly. Damage can take weeks to manifest, as well as improved health from improving the conditions.

Yes, I am with Purple...That is not damage from the sunlight..That is stemming from the roots...

Don't be tricked and please do as you were going to do with the advice others are giving you here-)

That could be salt damage, damage from over or under watering in the past too. I would make sure those plants are kept in a very nice open porous mix .

Good luck..