The member term can be edited in the campaign dictionary :
1) Go to campaigns admin panel.
2) Click on Settings tab and Campaign Dictionary tab under it.
3) Find the "Global - Member Term" item in the list.
4) Click on the item to make changes.
5) Click on Edit button on the pop-up.
6) Make the necessary changes and click Save button.
7) Refresh the site page to see the changes.