It looks like your files are associated with Win explorer by default..
Firefox has its own file handler, so please do check it first in Firefox settings, to start fresh you may also try by deleting/renaming the program handlers.json file in profile.
(I would prefer renaming the file)
C:\Users*****\AppData\Roaming\Mozilla\Firefox\Profiles\qmemsi27.default
the last folder might differ on your side..
Also make sure to reboot Firefox after any changes..
Edit: this is how it look in my handlers.json
"application/zip":{"action":2,"extensions":["zip","aia"],"handlers":[{"name":"7zFM.exe","path":"C:\\Program Files\\7-Zip\\7zFM.exe"}],"ask":true}
"application/x-zip":{"action":2,"handlers":[{"name":"7zFM.exe","path":"C:\\Program Files\\7-Zip\\7zFM.exe"}],"extensions":["aia","zip"],"ask":true}