Bluetooth on on RPi3B+ will not stay configured

I am trying to configure some bt devices on my installation on a raspberry pi 3b+ and have the problem that every time I do a full restart of my host (rp resrtart) I boot with not bt interface.

I am pretty new here so I have very little knowledge of the system and the underlying os, but my non permanent solution to enable bt till now is to go through the terminal add on and enable Bluetooth by running:

btattach -B /dev/ttyAMA0 -P bcm -S 115200 -N &

I tried some other solutions including editing the config in the mnt directory but I seem to not have access as I am probably doing something wrong (when in terminal if I type login I don’t know what username password combination I should use next to drop to a core ssh promt). I have set a root password for the ssh login on the ssh add on but this is it.

Any help is appreciated. Also it would be interesting to see why it seems to be only me having this problem. Or I didn’t read something well enough in the documentation. Maybe it has to do with me previously enabling the uart interface on the rpi3b+ with a previous os?