Folio size different

I have a project with 6 tabs/pages.

When I open the project I expect all pages to have the same size. This is not the case.

- page 1 = reference
- page 2 smaller than page 1 and shifted right.
- page 3,4 & 6 smaller then page 1
- page 5 smaller than page 1,3,4 & 6 and there is a top and left marging which is not there in the other pages.

It is not e big deal but irritating. Can this be helped?
This happens only with his project.  Other projects do not have this issue.

See attached picture.