Need help choosing a Photo Gallery plugin

I personally know nothing about WordPress, but I signed up for it a couple of months ago at GoDaddy. I tried to make a website, but figure out how to make WordPress work. What I DID succeed in doing was creating a photo gallery, with rounded corners, no borders, uniform photo sizes, on a black background which runs down the center of the page, revealing the multi-colored background behind.

Then I hired a website designer to take my work and finish it so the website looks nice. She did that, but now the photo gallery only looks right when viewed on Firefox web browsers! On all other browsers, the photos have square corners (sometimes with a white border), and each photo is a random size. She says I need a different plugin that can be viewed from all browsers – so here I am asking for help. After trying 3 different plugins, she says: “I used the NextGen Gallery (free version), the built in WordPress Gallery (version 4.4.2) and then the gallery that was built in to the base theme I am using (which is Atelier).”

What plugin do I need to have rounded corners, no borders, of uniform size, on a black background, that can be viewed on Google Chrome, Opera, Firefox, etc.?

https://wordpress.org/plugins/gallery-bank/