Modify message "Do u want to derive a new probation period" on changing assignment.

On changing position of a employee, the following message is displayed 'Do you want to derive a new probation period on changing assignment'?

I want to

1. Disable this message.

2. Stop system to calculate new probation period on changing assignment as our company policy is to calculate probation period from the date of hiring and not from changing position. 

Due to this we have faced multiple problems and probation of employees has been updated mistakenly.

Regards,