I’m running an older version of macOS from an external thumb flash drive stick [Mojave]. All of the sudden it won’t accept my password. It did at first but now it won’t. I didn’t change my password for this OS – it just went to sleep and when I tried to get back in it WILL NOT accept the p/w.
I have no idea what to do about this, so I came here hoping that someone in this community could possibly offer some assistance.

I’m running Catalina 10.15.3 on my 2017 MacBook Air, with Mojave 10.14 on the flash drive.
Appreciate any insights you may have….