I have all the options checked, but aircraft labels are not appearing either on my airplane or AI airplanes. Does anyone know how to fix this?

Take a look at this section of your FSX.cfg.  My labels are off, so 0's are shown.  Are your all 1's?

 

[AContain]
ShowLabels=0
ShowUserLabel=0
ShowLabelManufacturer=0
ShowLabelModel=0
ShowLabelTailNumber=0
ShowLabelDistance=0
ShowLabelAltitude=0
ShowLabelAirline=0
ShowLabelAirlineAndFlightNumber=0
ShowLabelFlightPlan=0
ShowLabelContainerId=0
ShowLabelAirspeed=0
ShowLabelHeading=0
LabelDelay=1000
LabelColor=FFFF0000
 

In addition to what Charlie said, I'd add the following:

 

1. Changes (selections) via the Settings Menu while in the cockpit / flight deck do not always stick once you've exited the simulator.  Always best to make changes by moving from the Main screen to the Settings Menu.

 

2. Even with labels turned on, I believe you still have to use the Command you established for the labels to appear.  You probably did this, I include it just to cover all the bases.

 

3.  I can't remember, but it may be that Aircraft Labels are tied in to the different Effects level (slider) so a lower settings may block the labels from showing.

 

4. Thinking back, I believe there were a few AI models that for some reason labels just wouldn't work for.  This might not be accurate, but it sure seems like i saw this many years ago.

 

 

Hope this helps you!  Happy flying!

Neither of your ideas worked, but I discovered I have an even bigger problem. I will be starting a new thread shortly. Thanks anyway.