After a fresh install of OP4, I first tried to change the WiFi password via the desktop gui. It seemed straight forward, but after a reboot neither the new or old password worded. Rather than putzing around with a wired connection, I re-flashed the OP4 image and started again. I first directly changed the WiFi password in /etc/NetworkManager/system-connections/OpenPlotter-Hotspot.nmconnection and all works well.
Edit: I am running on a RaspPi 5
Edit: I am running on a RaspPi 5