Thanks for the report. There was a Unity bug with dropdowns that forced me to work around it, but you should be able to change resolutions by pressing A on the option and then Up or Down. (X on PS, B on Switch).
Just opened it again after last night. When i closed it last night i had set it to windowed but could not adjust the resolution. Today it started from windowed mode and i could see the options to choose the resolution and select them now. Strange.
