https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

Many thanks for you help FredMcD !

I did some tests.

If I add manually the password in the fireFTPsites.dat, then it works. But as soon as I did a change in the account (change the account name for instance) then password is removed at the next launch.

And always the command "Remember passwords" is ticked. (no issue on that tick box)

Are you saying you have multiple accounts on one website?

https://github.com/hultmann/multifox/releases/tag/3.2.3 Multifox is an extension that allows Firefox to connect to websites using different user names. Simultaneously!

I think that FireFTP uses these files in the profile folder:

• fireFTPsites.dat
• fireFTPprograms.dat

Note that Firefox needs to be closed if you make manual changes to files in the profile folder.

Thank you for your input.

FredMcD -> multiple accounts setting is not the problem.

I've make some checks: actually Firefox does not remember any login/password at all. Neither for site nor fireFTP.

In Firefox > Options > Security

 - Remember logins for sites : Ticked
 - Exceptions is empty
 - Saved logins is empty

The problem is at Firefox level and not at FireFTP level.

I did a refresh; no extra tool bar; no anti-virus installed (except Windows defender security); no user.js file;

in prefs.js: user_pref("pref.privacy.disable_button.view_passwords", false); user_pref("pref.privacy.disable_button.view_passwords_exceptions", false);

If you think that it is about Firefox then you would have to look for fireftp prefs in prefs.js or on the about:config page if you can't find this data in the two files I mentioned above.

Otherwise you would have to contact the FirefFTP developer for support.

It is solved.

I followed tips from here: https://support.mozilla.org/en-US/questions/1065862

1. Close firefox
2. Rename the key3.db file
3. Rename the signons.sqlite file

Now Firefox remembers password. Logins are listed in Secutiry > Saved Logins...

Many thanks for you help FredMcD and Cor-el