To change the grades and pay scales on an employee's post:
Search for the employee and go to their profile.
Click Employment and then Position.
Click Post Details, which will take you to the post's settings page.
Scroll down to Pay Details and click on Edit.
Select the lower and upper grades from the Grade Lower and Grade Upper fields.
Select the lower and upper pay scales from the Lower Pay Scale and Upper Pay Scale fields.
Click Save.
Once completed, when adding a salary to an employee who is in this post, you will only be able to select a pay scale that is within the lower to upper pay scale range added on the post.