Correct. You need to be active and make posts in order for your activity to rise. FYI, your Activity can never be greater than your post count.

The activity number is determined in this way:
time = number of two-week periods in which you've posted since your registration
activity = min(time * 14, posts)

Activity is updated every hour.

You may earn maximum 14 activity points in every two weeks.  It does not count if you post more.  Thats why you may have less activity points.

This is the wrong section to post for that help. Your avatar has nothing to do with your badge or activity.  But if you give it a few minutes, the changes will take effect. Make sure to refresh, as well.

Press CTRL + F5 to refresh your cache and your avatar should update.
FYI, if your avatar is meant to be the Exscudo one, then it has changed.

I am new in this forum and it is very helpfull to understant the Bitcoin world and find opportunities
I have only some reserve about rules and definitions : I was searching about 1 Hour to finally find this topic
it is better to put in first position at home page or to add it (+rules + FAQ) to the list beside profile, messages, members, ....

Since the value of Bitcoin has gone up drastically, relative to everything else, shouldn't there be a decrease in the total BTC donation amount?

I do understand that argument. Having said that, It would seem very likely, that the donation amount was set depending on Bitcoin's value at the time of rules setting (maybe it wasn't).

Thanks for information its really useful for a newbie . Based on the time and activity period we must spend more than one year to get senior level. Its really Good concept in one year continues participation will improve lots of knowledge.

I agree with your answer being correct; however, I totally disagree with it.

What I feel is a shame is that some listed donation badges are scammers from long ago and they are not removed.  Any new company or legit person trying to get the badge simply can't because of the price of bitcoin.

Example:  In the beginning of donations, I could donate 50btc for a cost of about $500.  There is no chance I would donate $87000 today.
I can understand that it's nice to keep the list relatively short, but to expect 200 times the amount is absurd.  When bitcoin hits $10,000 is it still going to be 50BTC, You know, only $500k to be listed and have the badge.

This blocks everyone from donating.  That said, it also implies that bitcointalk.org is limiting the number of donations it gets.