As no answer after a week I presume tagging of posts is not a subject that is widely used and and is part of the korus system.
I will continue to tag my own posts as it gives me some control over finding my previous related posts.
Still unclear why the "my tags" option bring up change email address, which means there is no sysytem to view your own tags, just a common pool of all tags which has 3 pages and seems to be almost alphabetic and is found by clicking on a tag in a post then click view all tags.
The tagging system may be an old system dating back to 2010 and not used a lot on many current posts, but can be useful for searching because the search in "whole community" does not always find the answer sought, or link to previous posts on a particular subject. A tag can direct you very quicly to all posts related to the tag keywords and as such is a powerful tool, if you know how to use it.