For the .F77 file
f77 bottom of window
What? Thats not a Geany filetype, the Geany filetype is `F77` (filetypes are case sensitive) Are you loading a custom filetype?
For the .f77 file
.f77 bottom of window
Again, thats not a Geany filetype, none have a `.` at the start.
It looks like its finding _something_ as a filetype, but not the right thing.
What version of Geany? Do you have any custom filetypes?
PS you have been caught by the github edit trap, I added a couple of extra questions to my previous comment, but github doesn't email edits, so you missed them. Its always best to go to github, not answer the email.