All Gateway 500 devices use a default text setting when they come out from the factory. In most cases that text mode is ok already and you don't need to do anything. But if by your car the default text mode is not ok (only some Gateway menu elements are visible, or there is absolutely no text information displayed, you can only see track numbers), then you need to change it. If the default text mode is partly ok, then at least you can see some elements of the Gateway menu, so it is a little easier to find the text configuration submenu and to turn on the correct text mode. But if there is no text information displayed at all, you can only see track numbers (Track01, Track99), then you need to do all this blindly. But no worries, you can manage to do it.
An example: Let's say that you have a Mercedes car with the NTG1/2 radio head unit, and after you installed the Gateway 500 device correctly, you can't see any text information (Gateway menu) in 6CD changer mode, only track numbers. When the car and Gateway device are fully turned on, you need to press the mode selector button on the 'AUX-Box' Gateway accessory on-off 3 times. This automatically brings you to the text selection submenu. Based on the above table chart you can see that for Mercedes the recommended text mode is track 5 ('+Paging'). With the Next/Previous track buttons you can navigate up/down between six track numbers, you need to choose track 5, and then to select this you need to press and hold the Next track button. Now with this you have enabled the text mode successfully, and you can see the menu elements of the Gateway 500 ('AUX_GW', 'Source', ...)