The mixer section calls up a meny of EQ, volume, effects etc...
First choose the Vol/Tone page.
Then push the same button till you see the 16 SMF part numbers.
Select the correct line (the icons for the tones appear)
Push the up/down button to get you to the select window for that tone ....
Wait - you're coming over here in a few hours - I'll show you then ! Silly me.

It's not such a chore.