[Plugin: NextGEN Gallery] Thumbnails are so pixalated

I’m working on a site for a friend and I keep trying to rebuild the thumbnails and they look terrible, so pixelated no matter what size I try to use. I’ve changed it from 100×100 all the way to 300×300. The images are square to begin with and are 500×500. I have manual edited the thumbnails of the first two images and have edited the size of the first image to 300×300 as the example of the highest resolution.

Before I uninstall it and go to something else, anyone have some suggestions on how I can salvage the thumbnails and the plugin?

https://discotesting.com/sarah/?page_id=135

Thanks

https://www.ads-software.com/extend/plugins/nextgen-gallery/