How do I make the 'Puprpose' field mandatory on Expense Header

Summary:

How do I make the 'Puprpose' field mandatory on Expense Header and can I change the name from 'Purpose' to 'Employee Description' for example?

Content (required):

How do I make the 'Puprpose' field mandatory on Expense Header and can I change the name from 'Purpose' to 'Employee Description' for example?

Version (include the version you are using, if applicable):

21D

Code Snippet (add any code snippets that support your topic, if applicable):