@docent31
As viktor mentions, the exact file is here:
nano /home/pi/.screenly/screenly.conf
You can edit the [auth basic] section if you forgot your web admin password by setting both lines to simply something like:
[auth_basic]
password = passwordyouwant
user = admin
restart the screenly services by running sudo systemctl restart screenly-*
and when you visit the web URL just type in admin and passwordyouwant and it should let you in.