I believe it gets set back to 1, when parameters are saved in the UserCfg.opt file, when MSFS is closed via its menu system.
One way around this is to start MSFS with a bat/cmd file, and there, before starting MSFS, do a search/replace on the UserCfg.opt file.
This is what I use … (remove the .pln - its a Text Cmd file, so you can check it yourself before running it)
BONUS: You get a MSFS Startup Splash Screen 
MSFS2020SplashScreen.zip.pln (67.4 KB)
( yes, the search replace is very CRUDE, but it works, and is “simple” – and easy to EDIT !!)