How to make default contact image selection?

[Anxious Gamer]

I have a Samsung Galexy Amp 2, and I was wondering how to have the default contact image app (Gallery) replaced with this newer better one I downloaded.
Everytime I try to open Gallery, it doesn't work. I tried everything, and it doesn't work, and I want to change my contact images.
So, I downloaded a new gallery app, in hopes to be able to use it to change my contact images, but that didn't work.

So, is there a way to use the other Gallery App to open in Contacts, or even to remove the stock Gallery App entirely?

Thanks