Note that outputs of channels 3 and 4 are switched on this revision. You can simply cut the traces that go to the tip pin of the jacks, cut them and then reconnect them properly with some wires.

Important: Absolutely make sure to use the 8x8mm Self Lock switches (they should have a blue pin where the switch cap goes on). Do not use the 8,5x8,5mm (white pin, black and grey body) as they have a different Pinout and will potentially damage your power supply. To make sure you have the right switches installed, check that there is no continuity between +12V and -12V in both switch positions before installing the module in your case.