Bulk update of Debtors Manager Invoice Reminders Opt-in

SOLVED

Good day

I am assisting a company who uses the Debtors Module, however they are struggling to get the Outstanding Invoices Communications Run to work because all customers are unticked on the boxes marked "Send Outstanding Invoices Reminders" & "Send Overdue Invoice Reminders":

I would have assumed that on signing up to the Debtors Module they would have been given the chance to bulk opt-in all customers at the time, but unfortunately they say this option was not given. Updating the customers manually one-by-one is not an option, as there are nearly 3,800 customers, the majority of whom existed prior to the loading of the Debtors Module. 

Is there a way to log a request to bulk update these 2 options in the back end for all customers on file please?

Thank you.

Stacy