You can amend the post name or the post title.
Amend the post name
Go to Settings and then go to Module Settings.
Click HR and then click Post Title.
Search for the post that you would like to change the name of.
Click on the name of the post.
Change the name in the Description field.
Click Save.
Amend the post title
Select Admin Menu.
Click Post Setup and search for relevant post.
Click on the line for the Post.
Click Edit in the top right of Basic Details.
Change the name of the post in the Job Description field using the dropdown.
Click Save.
If the name you wish to change it to is not available, you will have to add the post title.
Follow the first set of steps as far as Step 5, then click Add New to the right of the job description field.
Enter a name in the Description field and unique code in the Code field.
Check against the existing codes of posts to ensure the code you are adding is unique. You can also add a Job Description and assign it as a manager role here.