[Plugin: NextGEN Gallery] Thumbnails resize only in width

Hey,
I use a nextgen Gallery to show gallerys on my website.

My theme is responsive (resizes with browser size) so when I view my gallery on a mobile, it has normal heigh but its very a few mm thin.

So there are 2 possibilities that I see:
1. Is there a way to set the colums not fixed, so that there can be as much pictures in a row as there is space?

2. Is there a way the thumbnails can be resized in fixed proportions?

The photos get shown right with lightbox (they resize correctly), but the thumbnails don’t.

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