That is not the export window, that is a track header, to the left of the track.
When you go to the menu File>Export as WAV, you have dropdown menus. Once they’re set, they should stay what you selected last time, so it’s sort of set and forget.
If you go back into Preferences, again under import/export, you can set the defaults for project settings. Make that 44100 (a.k.a. 44.1kHz) 16 bit as well and new projects will open that way from now on.