This I'd guess is important, if you have several users. I don't, except
for amanda and nut, and thats only on this machine. All the rest have
one user, me, known under various aliases because the idiot installer is
now set to give the first user the machines name like pi or rock64. I
spent a month trying to fix user 1000 to be me instead of pi on the pi.
On the Pi, this is what worked for me:
1. Add a new user (and add him to group sudo). This user gets ID 1001.
$ sudo adduser tempuser
$ sudo adduser tempuser sudo
2. Log out of user pi and log in as the newly created user.
3. Delete user pi (pi must not have any processes running)
$ sudo deluser pi
4. Add the desired username:
$ sudo adduser gene