Can’t change the YouTube video tags

I’m trying to fix something with the tags, but it seems like it doesn’t anything.
I’m changing it in the video options, but after I’m pressing on “save changes” and it writes “Video details have been updated!”, it keeps the tags the same.
Is there a way to change it?
Edit: I tried to add the number “2” as a single character and it probably just doesn’t support a single-character tag because a longer word worked, so it’s probably not a bug.
Answer #1
…? No one knows?
#3.5 Bumping is allowed provided that the reply has relevant information that is useful to the continuance of the topic. Short intervals of bumps are not allowed to bump the topic up onto the first page by the same person.
Example:
Allowed: A topic discusses a news event. The topic's discussion has died but there is new striking evidence to turn thoughts around. A reply with such information that is relevant and useful is allowed.
Allowed: Requests may only be bumped once every 48 hours since the last reply.
Disallowed: A one-liner reply with the words "lol".
Disallowed: Bumping topics continuously to get them up to the first few pages.
glenny.