Opted to start in full screen now I just get a blank screen when I try to run the game. How do I move it back to windowed mode?

Last update: 2022-07-11 - Announcement Game engine update. Gamepad control has been improved. Minimap of the locations has been drawn. Changed main menu Added Achievements, Settings and Cyclopedia submenu in the Pause menu! Bug fixes Completely changed savegames! dodge ability added! Plans: Arena with endless enemy waves [/lis...

I've managed to get the 'all secrets' achievement and all the parts to assemble the jade key but I can't find any place to use it. I feel like I vaguely remember a green skull door somewhere but a quick runthrough didn't help.

FATAL ERROR in action number 1 of Step EventoSpell_Heven_Lightning for object pMob: Push :: Execution Error - Variable Index [0,-1] out of range [1,21] - -1.Gun_BulletObject(100202,-1) at gml_Script_scrWeapon_CreateBullet ############################################################################################ -------------------------------------------------------------------------------------------- stack frame is gml_Script_scrWeapon_CreateBullet (line 0) gml_Script_scrWeapon_Proc_HevenLightning gm...

im lost.. what do i do.... i just killed first boss.