Hi krispy
What version of MYOB Payroll are you using? - your print screen doesn't show the annual leave in weeks. It should.
You should change the normal hours per day now to 8 which will bring the annual entitlement to 160 hrs (4 weeks)
This will fix the accrual for the last 12 months and give her new entitlement on the new basis on her anniversary date. You will also need to increase her annual leave due to a calculation @ 40hrs per week (143hrs equates to 4.08 weeks - this will need to be increased to 163.20 which is the 4.08 weeks at 40 hrs per week. Regarding the overpayment of annual leave paid since 1/3/20 - I think you would have little chance of getting this back, but a discussion could be had to recoup this cost.