Using this table, you can change the primary sysadmin responsible for billing for the designated tool for this account. To do so, select a different account user with a radio button and press save.

Note that you cannot edit the particulars about the primary sysadmin, for example, his email address. You must do that the same way you change the particulars about any user, by clicking the edit pencil to the right of the several places they are listed as individual users.