How to get access to all files while doing ssh?

To change my static IP address, I need to edit `/etc/dhcpcd.conf` by running `sudo nano /etc/dhcpcd.conf` however, if I am connected as `biqu` , it tells me `access denied`. To make this working on a btt-pi2, I need to connect as `root` with the password `root`. But this doesnt work on the btt-pi v1.2

Start with the reported command and `/etc/dhcpcd.conf`, then compare SSH access and root-login behavior between the btt-pi2 and btt-pi v1.2. Done means identifying why `biqu` receives access denied and documenting a supported way to edit the static-IP configuration without relying on the reported root credentials.

Written by the indexing model from the issue text.