You can customize your hourly rate per time entry, or set a default hourly rate in your personal settings.
Please watch this video or see the steps bellow:
1) In order to set your default hourly rate, go to your personal settings.
2) Under "Time Entries", at the bottom of the screen, you'll find the "Hourly Rate" field.
3) Fill out your default hourly rate, then click "Save".
Set custom rates by creating/editing a matter and select "Matter Custom Rate".
This will allow you to set a default matter rate, a custom rate per user, or per role.
What happens now?
The hourly rate for your matters will be whatever you have set in your settings page. If you've chosen a custom hourly rate for this matter, that will autofill instead of the rating in your settings.