When I go to LR Classic on my imac Big Sur Preferences > Presets and change the camera to Fuji X100V and then close preferences and then re-open preferences>presets the camera shows my iphone X even though it is not connected to the imac.
How do I get the camera presets to stop changing the camera presets?
The camera model showing in Preferences Presets is for the currently selected image file. You most likely have an image file from your iphone selected. Try it with a raw image file from your Fuji X100V selected. More here:
At the link I provided it explains your Raw Defaults settings options, which are Adobe Default (by default), Camera Settings (your in-camera settings), or Preset, which allows you to create and use a preset to define the Develop settings you want applied on Import. When you go to Preferences> Presets with a newly imported raw file you should see your camera model in the Camera selector. Unfortunately, there is a bug with the 'Default' setting display, which always shows 'Adobe Default' regardless of the setting you manually applied for that camera model. In addition there is a rather long delay (5-10 sec.) before the camera model and setting fields are initially populated and the settings panel is too narrow. I have created and assigned Default Develop Setting presets for all of my camera models so that I can apply custom camera profile, WB, and Detail panel settings on import.