So what exactly is unchecking the box supposed to do? It looks the same for me?
If you are in the ModTool click on Code and Look for the gml_Globalscript_src_set_game File. When you Double click it a decompiled Code should Show Up. There in the Global classes at the top should be global.coin . That is youre starting Mana so If you Set it to 1000 you start with 1000. Hope this helps 😁