Create invoice, item line, how to change unit from "months" to "hours."

[SidKemp]

I used to bill hourly. Now I bill monthly.

On the item lines of my invoices, the unit being billed is "hours." (I set this up many years ago and don't know how to change it.)

I want to set it up so the unit is "hours" as a default.

Can anyone tell me how to do this, please?

Thanks,

Sid