You can use the options in the checkout widget to set allowed payment methods and control the amount paid settings.
To access the settings of the checkout widget:
Go to settings --> forms --> hover over the form with the checkout widget --> click into the widget.
A side panel will open and display the widget options: 
Widget Settings:
Allowed Payment Methods:
- You can disable/allow ACH and Credit Card payments
- You can set the default payment method as ACH or Credit Cards
Saving Payment Method Options:
- Choose to auto save the payment method entered for the user for future payments (like autobill or one-time charges)
- Decide if you'd like to show/hide the checkbox allowing for the payment method to be saved on file
- Allow for Manual payments so users can bypass the checkout step and send a check or cash by mail
Amount Settings: For group or family systems, these settings give you control over how users can include or exclude payments on the checkout form for all users in the group.
- Disable the ability to exclude ANY user when issuing a payment: You can turn this setting on to force the user to pay for all open balances of their group. Off is recommended as it allows for flexibility for the user when making a payment to exclude some of their sub-unit's payments.
- Disable the ability to exclude the current user when issuing a payment: The default will exclude all user payments other than the current user when reaching the checkout form. If you would like to prevent the end-user from removing the current user payment from the checkout, turn this setting on.
- Allow users to change the amount presented: This shows a field that allows users to change the amount of the current payment. By default, the system will show the balance. Turning this setting on allows the user to change the amount to pay to any amount they choose. We do NOT recommend this as it can affect your revenue and cash flow.