I do not use distro releases of Mozilla Firefox, Thunderbird, or Google 
Chrome, but rather updating to current production (not beta) from the 
actual provider.

In the past, when, say, Firefox would announce that an update was 
available but that I (as myself, not root) did not have sufficient 
privileges to update, I would exit the application, switch user (not 
sudo) and login as root in MATE, activate the application, perform the 
update, exit the application, and then switch back to my ordinary user 
account.  Upon so doing, I would activate the updated application, and 
verify that I was using the latest updated release.  This always used to 
work.

Now, when I switch back, although the application is not revealed by ps 
(under any UID, not just mine), the pre-update version is still in use 
until I actually logout and re-login (not just switch user). Thus, 
although the application is not in use when it was updated, a login 
session (at least through MATE) must be caching the "old" binary 
executable image, and not loading a fresh updated one from the file 
system.  Other than log out and log in, is there a mechanism for 
"flushing this one application entry from the cache"? Currently, SL 7.8 .

Take care.  Stay safe.

Yasha Karant