Can't delete any pictures?

I am having so many problems with Product Cart.

My images ALWAYS are blurry once on my website, compared to my actual images that I am uploading. I have never figured out a way to change that.

I thought that maybe it had something to do with having a huge database of old photos from products I no longer have. So I tried to begin to delete them. Didn't work after 4 tries.

Do I really have to go in and check off each one, one by one, detail, general, and thumbnail to delete them?  Why can't product cart be more visual and intuitive?

I tried 4 times to delete the SAME PHOTOS and they wouldn't go away. Whenever I was done, product cart just took me to a page that said "back". When I hit back, I still had the same number of photo pages. Sure enough, all the ones I had checked off to delete were still there.