If you wish to navigate up and down across Groups, you'll need to re-purpose two of the ES-5's on-board switches to control the Group Up and Group Down functions.
As far as which switches you choose to re-purpose, unless you wanted to re-purpose two of the Effect loop footswitches, you would most likely want to choose the BANK and MUTE buttons.
Assuming that's the desired configuration, here are the steps to set it up:
1. Press EDIT.
2. Press the Left/Right Arrow buttons to get to: CTL/EXP.
3. Press ENTER.
4. Press Left/Right Arrow buttons to get to: BANK.
5. Press ENTER.
6. Press (+) once to select: GrpD (Group Down).
7. Press DISPLAY/EXIT.
8. Press Right Arrow once.
9. Press ENTER.
10. Press (+) button three times to select: GrpU (Group Up).
11. Press: WRITE three times to save your changes.
PLEASE NOTE: This fooswitch assignment configuration must be set up for every Preset that you want to use it with.