You can modify a WHM account by following the steps in this guide:
First: Log in to WHM
Second: Go to Account Functions
Third: You can locate this quickly by searching for Account in the search bar and go to Modify an Account
Fourth: Select the account that you'd like to modify
Fifth: Click the Modify button
Sixth: Adjust the settings as you'd like and click the Save button at the bottom of the page
If you get the "Package Conflict Resolution" notice, which can happen if you don't have a package with these settings, choose the "Keep this account on the package" option. Yes, it may say it's not recommended, but this is actually the best selection. Other selections could result in other packages being changed.