Trying to hide a big scratch on iPhone 6S screen I've always been a "naked iPhone" kinda guy since I love the design and hate the way cases feel in my pocket. I've managed pretty well for the past 6 or 7 years, and even when I DO get scratches I don't really mind. My latest iPhone, though, somehow got a pretty large scratch across the front (and a smaller one above that).

The thing is, I'm worried that I won't be able to trade it back in to T-mobile with a big ugly scratch on the screen. I know there's no way to "fix" a scratch, but I'm wondering if there are ways to lessen it--or at least make it look better. I've googled this several times and come up with things like toothpaste or vaseline, but I've also read that some of these things can make the screen worse.

I've also read that screen protectors can make scratches look better (and I've already ordered one), but when I return it to T-mobile I'll probably have to take that off. 

Note: I've included a picture of the scratch(es) below, and the slight blurriness of my iPad camera does make the scratch look even worse. Just keep in mind that it's a big scratch, but not quite as deep and nasty as the picture suggests.
Based on your included picture, I feel that it would be best to research whether T-Mobile accepts this type of return. On the other hand, I think that it would be better off if you just show it as it is, because if they find out that you have hidden a scratch, they might deduct cash. I think you should just trade it in as it is. Even so, http://www.t-mobile.com/cell-phone-trade-in.html states that your device's trade amount will be determined inside the store. So, just leave it as it is.