Why does editing a new page overwrite changes on my initial layout?

Hello everyone!

I am experiencing issues with editing each page on the theme editor page. Basically, when I get one page just the way I like it, I hit “save changes” and try to move on to the next page where I can edit (add slideshow, collections list things like that) and when I am finished editing my second page and hit save changes, it overwrites all of the edits I made on the first page. I don’t understand what I am doing wrong and why I can’t make more than one page.