"old firefox data"

Hello everyone,

I am considering uninstalling Firefox 85.0 and properly installing the older version: 63 or another similar one to maintain control over this browser.
In the folder and file hierarchy, it turns out that there is a file called "old data", I know that it is actually necessary to restore the missing data after a Firefox update.
Could someone explain to me what I need to do!!! This operation is certainly feasible.
In a time when everyone helps everyone, I hope I will be helped
P.S: I don't know how to back up favorites and bookmarks as well as browsing history.
Best regards.

Configuration: Windows / Firefox 85.0