Hi rexi
I feel like I just answered that.
Instead of F1 you can press the ? key.
Instead of F2 you can press the / key.
If you press the ? key, this help menu appears:
It shows:
Instead of F3/F4/F5 you can press the Tab key to cycle through the view modes.
Instead of F6 you can press the s key.
The Left/Right arrow keys select which control to adjust.
The Up/down arrow keys adjust volume.
The +/- keys adjust volume.
The Page Up/Page Down keys adjust volume in big steps.
The rest of the menu item meanings should be clear.