When should we use ByVal and ByRef in VBA?

Answer 1

ByVal basically makes a local copy and keeps only the value at time of assignment.

ByRef connects the assignment to the original variable.

You use the former to retrieve a value for further procession.

You use the latter to repeatedly query a value in the original variable.

Also, if you define a variable ByRef, and assignment or modification to that variable will also change the original variable.