Hold down the middle button to enter the settings menu and select the TARIFF option. You can set up to three tariffs and a standing charge. Use the – and + buttons to change the tariff value and then middle button to save the changes.
Most customers have a single unit rate (A) and a standing change (X).
If you have an Economy7 meter then you will need to add your second tariff rate (B – night rate) so that your monitor displays daily costs accurately.
Your monitor has the option for a 3rd tariff rate (however this is only required for a very small number of customers).