Blog Summary Page Problem

I’m developing a custom wordpress theme blog for a company and I’m having problems with the posts page (which I’ve set in Settings > Reading > Front Page Displays)

My blog index template is home.php but it won’t update whenever I try to make changes on the file. Up until I tried to create a new page and set that as the default Post Page with the url /blog-summary. Since I wanted the url to be /blog, I changed the new Post page url to /blog and deleted the old one. I thought all will be fine but then it changes template again to which I don’t know where it gets from.

I tried deleting both index.php and home.php but the page remains the same. I tried changing file names, changing themes, I tried deleting my local cache, I even removed my caching plugin but it still doesn’t change. The other pages reflect the changes, though. Can someone give me a suggestion on how I can use /blog url? Thanks in advance for the suggestions (sorry if my engrish is bad, i tried to explain it the best I could :c)