FlexiTime calculates Holiday Pay as a percentage of an employee's Gross Earnings. 8% is the equivalent of 4 weeks Annual Leave per year, 10% is five weeks per year.
To change an employee from four to five weeks per year, edit the employee and select the Leave tab, then update Holiday Pay % from 8.0 to 10.0. To change to six weeks per year, enter 12%.
If the employee has been accruing a different number of weeks before the change, so has an existing holiday pay balance then changing the holiday pay % will re-calculate this balance. You can find the difference between the old holiday pay accrued and the new holiday pay and enter it into the Holidays Paid (Pay as You Go) field.