In the latest iteration of Thunderbird 115.4.1 the main window header normally containing 'File, Edit, View...' is now below the Menu bar. Not sure why that happened but I can't find any way to put it back where it was. It seems odd that this program should be any different than every other windows program. Firefox still has 'File, Edit,View...' at the top of the window.
I expect it should be an easy thing to change, or at least provide an option to have it where it used to be.