Permalinks cannot be edited for page in settings or on page

What do you “still have not been able to change it”? Do you see an error when you save it? Does it save, but post/page links now go to 404 errors? Does it just revert back to default?

That’s not a permalink, that’s your domain.

What do you expect it to be instead?

You want your site to load at http://callumhey.com/film instead of http://www.callumhey.com/ ?

Or, do you just want the content of the film page to be what people see at http://www.callumhey.com/ ?

Ok, you’ll need to move WordPress then.

Make sure that you follow each step in this guide: https://codex.wordpress.org/Moving_WordPress#Moving_Directories_On_Your_Existing_Server