A "selector button" refers to a button or switch that allows you to choose or select different options or modes on a device or machine. It helps you to easily switch between different settings or functions. Full definition
The hard plastics used for, say, the gear selector buttons just don't feel premium. (autoweek.com)
As already mentioned, HMI is one, and a related issue that the new car appears to have addressed is the positioning of the gear - selector buttons on the central console: in the 12C and 650S to get to them you have to do an impression of a T rex. (evo.co.uk)
With the console - mounted mode selector button set to track or sport the steering gets less boost for greater feel, the ride is firmed up, throttle response is increased and the eight - speed automatic shifts more quickly. (autoweek.com)