in [daemon] add MULTIPASS_STORAGE support (Fixes #1215) I find how to change the location. So I create the file /Library/LaunchDaemons/setenv.MULTIPASS_STORAGE.plist and activate this with launchctl load /Library/LaunchDaemons/setenv.MULTIPASS_STORAGE.plist but new instances do not use the new location.
my problem was not with the /Library/LaunchDaemons/com.canonical.multipassd.plist. I finally found that for some reason the /Library/LaunchDaemons/setenv.MULTIPASS_STORAGE.plist was not correctly loaded. After I load /Library/LaunchDaemons/setenv.MULTIPASS_STORAGE.plist again it works!