The Payment Method determines the default for an Account used when executing a distribution.
Step 1: Navigate to the relevant Account. See below two options to use either the Global Search or Accounts page.
Step 2: Review the current Payment Method under the Payments section. Select the ellipsis (three dots) to the right of the Account name and "Edit Details".
Step 3: Scroll to the bottom and select the Default Payment Type from the drop-down. The "Auto Payment" selection will send an ACH when possible and send a check if no linked account exists.