How do I overwrite an existing radio preset with a new one?

If you have a station saved in a particular preset number and then decide to replace that one with another station, please follow these steps:
Whilst listening to the station that you want to save in place of an existing preset, press and hold the 'mode/store' button, you can then use the 'search' buttons (picture attached for reference) to select the preset number that you want to use/overwrite.