As Firefox introduces changes in order to appeal new users, some current users might prefer the prior behaviors. Here is a selection of changed features and how to undo / work around them.
- Viewing a selected image in the same tab has been removed.
You now need to use an add-on such as View Image Context Menu Item.
You can vote to revert the feature there: Firefox : Bring back "View Image" - Mozilla Connect
- In the preferences, in General > Applications, change the action for the given content types.
- Since 101.0: a setting right below the known content type list now allows to chose the default action for unknown content types.
- Since 102.0: In order to use the system temporary folder when opening files, instead of the download folder, change browser.download.start_downloads_in_tmp_dir to true in about:config.
In about:config, change extensions.unifiedExtensions.enabled to false, then restart Firefox.This option was removed in version 111.0.
You can vote to revert the feature here: https://connect.mozilla.org/t5/ideas/please-let-us-move-the-new-extensions-button-into-the-overflow/idi-p/22979