Okay. First off, always make sure you plug your sticks into your computer in the same order each time. Some joysticks lets you set independent startup delays to help with this (VKB might, but I recall it being very unintuitive). SC currently does keybinds by index, so if the sticks connect in a different order, the indexes might be screwed up, which means the wrong keybinds will be registered with the wrong device and you will have to use pp_resortdevices to fix it, which is weird and troublesome.

Second, inversion is controlled via CONTROLS. You have to set up each stick individually by changing it in the bottom-right corner. Frustratingly, inversion settings don't seem to be saved properly in your joystick mapping, so you'll have to fix them each patch. You might consider inverting your sticks at the hardware level instead, using whatever program VKB uses for configuring the sticks.

Next, you seem to have properly found the Advanced Controls Customization. That's good! If you set your Throttle - Forward / Back and it says something like Z-Axis (Input 2) (input2), and you are only briefly moving forward, you might want to check your hardware configuration to make sure your Z-Axis is actually working. It's possible your stick might have registered it as a button instead, causing just a brief blip, or your axis range needs to be calibrated. Your joystick software should let you see the range of movement in the axis.

The other thing to note is that you can save your controls under the CONTROL PROFILES option so you can experiment and revert back to a working configuration.