Changing FN to Monthly Leave Accruals

Hi Everyone, 

I have just transferred a fortnightly paid, Part Time employee working 30hours per week,

to a Monthly paid role working 38 hours per week (setup as 164.67 hours average pm). 

I am trying to ensure her leave balances are calculated correctly and appear accurately on her pay slips going forward.  

When I try to update the [Wages Information] page to reflect her with the "Salary setup" - I see this message in my attachment:

Could someone please help me understand if making this change affects JUST the employee I am updating or EVERYONE on the monthly payroll?  

I also want to check the box that auto deducts leave taken as it is used during each cycle, but this message is also scaring me off! Can someone confirm how I ensure employees have hours auto deducted? 

Grateful for any support from the community.

Thanks 

Suzy