Macbook Mic as a default and F-keys config

[phl92]

I am new to MacOS and I tried to figure it out myself with the Apple Guide Website but I can't.
I found the Sounds settings in my MBA M1 under "sounds", where I can change output / input devices. However, when I select my MBA Mic and then connect with my AirPods Pro, it switches automatically to the AirPods again as a Mic. How can I set, that the Mic is always from the laptop (it much better).
Another question, when I press F5 I thought I can immediately make a Voice Memo. But this is not the case. It enables Voice Dictation for Text which I don't really need.
Is there a way to configure the F5 keys individually, like open up specific Apps like the Voice Memo or other Software? Under Keyboard settings I find only a very limited possibility.

 

[phl92]

Ok today was a big test for my new MBA and I worked all day in 6 video conferences (most Skype) and around 10hours work with Mic/Airpods Audio.
Every time I put my AirPods off or disconnect them, the default settings of Sound settings in MacOS go back. That is super annoying, especially because switching the Mic to the MBA Mic during a video called caused several times for issue (it caused weird sounds of the voice of my Skype partners).
So how can I fix that I always want my Mic of my Macbook instead of my AirPods? Isn't this logical? I mean the AirPods sound crap compared to the Mic in the new Macbook.

 

[phl92]

someone?