Using on screen menus on Carminative screen

Hope somebody can help .. Just taken delivery of a 2014 Tom Tom megane sport tourer with standard head unit and carminative sat nav screen. I've managed to pair my phone and can advance through the menus to make/end calls etc and I can 'go forwards'through the menus when browsing a USB music dongle .. My problem is that the instructions do not appear to show how to go back a step in the menus - eg if I enter my phone book and view a contact with initial A, how can I return to menu to change the initial to B etc .. Same with the USB menu, if one album is selected how do you go back to,the main list of albums

Thanks