But I noticed an other strange thing. Now I get a grub menu only if I do a cold boot. When I do a restart of the computer grub menu is never displayed.
Is it supposed to be like that? Can I get a grub menu in both cases?
I don’t know if this is your case, but starting from F29 it is supposed that the grub menu is hidden by default.
Have a look to this document: https://fedoraproject.org/wiki/Changes/HiddenGrubMenu maybe you can understand if this is what you are seeing.
I’ve marked the solution on your behalf so that others experiencing the same issue may find it quickly.
Please go through the posts in #start-here if you haven’t had a chance to do so yet. They provide short summaries on using the platform (Discourse) efficiently.