You need a couple of alligator clip jumper leads,
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they are available many places any auto parts store as well as Harbor Freight and such.
They will aid as they will grip your meter leads and wires or terminals.
With your actuators disconnected open your switch box and verify 12 volts to both switches on one pair of contacts.
From your previous pictures I would say the pair of contacts in the middle of the switches.
Then with your leads on the other pair of contacts toggle the switch one way your meter then should read 12 volts, let the switch return to center and you should be a zero volts, toggle the other way and you should have the same voltage reading but with polarity reversed.
As you operate your switches you should be able to observe the polarity change from + to -.
That will verify your switches, then start tracing out your harness wires and get the correct pair going to each actuator.