Can't change membership-level as admin

As Admin I can select the membershiplevel of any user, but there ist no button to save the changes, only a button to cancel.

I have a second test-installation on the same server where this is working well. As far as I can see all the adjustments in both installations are the same.

What have I missed?

Yes there is!!

Once you had change membership go down in the page and save changes. I think it should work. You can not see the button becouse there is only one for apply all changes, but down of the page.

Yes, you are right - thank you very much and shame on me .

1 Point for you!