As an Account Admin you can click on the Account and Settings menu on the upper right corner of the screen and then select ‘Users & Groups’.
From the ‘Users & Groups’ screen, click on the pencil icon by the name of the person for whom you need to edit the credit limit.
When the Edit User screen appears, click on ‘Purchasing’ under ‘User Profile’ on the left, from there you can assign the user a revised credit limit up to the amount of the company’s credit line. If the user already has open charges and authorizations, you will not be able to edit the credit limit to an amount below the this amount.