need help with multi disk games on my GDEMU?

[dreamcast459]

i have a gdenu and have used gd menu card manager alongside openmenu im playing some games with mutli disk how do i switch games i mean i know i press the physical button on the gdemu but how do i know which game the buttom is selecting? example if im playing code veronica X how do i tell the gdemu to load diskl 2 of code veronica instead of say crazy taxi?