I installed profile switcher, and followed the instructions for adding the "additional software." I checked the output of which firefox and it said /snap/bin/firefox, so I ran the corresponding script. However, nothing has updated for me, it still reads the same prompt about adding the additional software. I also checked my ~/snap/firefox/common directory and it appears that all the files from what I gather the script installs are there:

Outputs:

ls -a ~/snap/firefox/common:
. .. .cache firefoxprofileswitcher-install .mozilla

ls -a ~/snap/firefox/common/firefoxprofileswitcher-install:
. .. ff-pswitch-connector

ls -a ~/snap/firefox/common/.mozilla/native-messaging-hosts
. .. ax.nd.profile_switcher_ff.json