You need previous configuration backup and downgrade resetting configuration (or much slower - back up now, downgrade with config reset, and unzip the backup file and type back all configuration via LuCI web)
Yes, you can downgrade resetting configuration.
For simplest usage - edit both wifi radios with country code, set channels to auto, edit both openwrt AP-s with your security (do not lcick anything else around), save configs, check again if they look as intended, and enable both wifi AP-s.