What you reported is an old situation that am familiar with ,and there's probably old posts about it still to be found here.
After my inital response I had thought to edit my post, but I hesitated because it appears that the forum is currently over zealous and prone to detecting spam when there is really none, so I decided to wait.
Irrespective of what John wrote, I had the intention of answering you, with what my edit was going to include.
Which is,perhaps you haven't noticed the change is its because its connected to refreshing the game.
If you change and don't refresh nothings going to happen so you won't see the change. Then later you may, and hence the confusion.
I have just confirmed this, you can try it yourself if you like.
As to John, I would suggest that his 'it doesnt happen isn't correct'.
The reason he doesn't notice this, is probably because all his Shaman are equally developed, so have the same influence to add to the total influence.
I also just confirmed this myself.
Shaman at the same level have the same influence.
Shaman at higher or lower levels have corresponding values.