Guide

1. Login to your WordPress account and as you can see WordPress is "6.6 version".

2. Navigate to "Plugins" and click "Add New Plugin."

3. Search for "WordPress Downgrade", click "Install Now", and then "Activate."

4. Activate the plugin by going to "Settings" and clicking "WP Downgrade."

5. Type in the version you want to upgrade/ downgrade to and click "Save Changes."

6. Select the "Up-/ Downgrade Core" button.

7. Then, choose "Re-install version 6.5.5" based on your selected version.

8. You've successfully reverted or upgraded your WordPress version as desired.