Start with one thing at a time and always make sure that what you are mapping, is not already mapped in the Simulator to another Control/Device.
Even before you test things in the Simulator, go to Device Manager and do a simple Calibration. Many devices, even new ones, can come defective from factory or with dead zones (areas where the controls do not respond or do not reach). In the Game Controller settings for the device, make sure your axis and all buttons work properly. Once you verify everything here, then move to program in the simulator. For Logitech Panels, make sure you download the adequate Drivers (Windows version x32 or x64, and install the latest version).
All your devices will show up in Devices and Printers. The Pitch Trim Wheel is an Axis. So when you select the Device and then look for the Setting and validate (Ex. Flight Control Surfaces, Elevator Trim) and assign it. Finally, make sure to turn off any assistance like Auto Rudder, etc., so they don’t interfere with your controls (Piloting Menu).
Actually the Logitech panels will not show up and can not be configured inside MSFS. They work “out of the box” (although not perfectly, depending on the plane).