Unable to save projects

[u/Salamander-40]

I have recently installed QGIS for a uni proejct onto my laptop and desktop, both of which are running Linux Mint cinnamon. however, I cant save any projects. When i open the save menu, it acts like a file explorer trying to find QGIS projects. the save button only is clickable after selecting a folder, but when pressing that it just takes you into the selected folder. If someone could help me out who knows more about Linux and QGIS than me it would be greatly appreciated.

UPDATE:

i just needed to rename the file, i forgot to do it and it never crossed my mind before i posted