Any other user works whether they are regular or owner just not the one created during installation. This was a regular user in the screenshot. I blanked out the QR code etc
OK… So, you can reset your admin password with
cd /var/www/mastodon/live && sudo -u mastodon RAILS_ENV=production PATH=/opt/rbenv/versions/mastodon/bin bin/tootctl accounts modify <your admin account> --reset-password
You will be given a new password and be allowed to change it in the webinterface or set 2FA but I don’t know if it won’t break something. AYOR.
I got the new password and it still didn’t work initially and then it did. Thank you so much 
I now can’t log in, but I can change details where I am still logged in. So it’s the opposite of my original issue. I’m so glad I added a second owner account 
The YNH admin password will always be the one used to log in to Mastodon (<LDAP), but only the password set with the Mastodon CLI will allow to change Mastodon settings.
Did you choose the same password for your Mastodon admin as for your YNH admin ?
Everything seems to be working now. Thank you so much for your help