As of October 2021, Clover does not allow the adjustment of tips on third-party orders
When a customer is checking-out online or on your app, they will be prompted to select $0.00 tip, 2 suggested values of your choice, or to enter a custom tip. If a customer does not elect to leave a tip before finalizing the transaction, they will only be able to tip in cash or by opening another transaction in-person.
This is a change that the teams at Clover made in order to protect the business, and most importantly, the customers from fraudulent activity. Here is a message from Clover:
A sale is a customer transaction where the purchase amount is authorized and settled at the same time. While a tip amount can be added, it is permitted only before the transaction is authorized and settled.
For additional questions about why this decision was made, or to learn how you can remove the tipping on paper for third-party orders, please contact the Clover support team.