I took off the transmission pan to change the filter and one of the metal hoses inside was very loose. I could push the outside end on easily but cannot get the inside end to go in all the way. Do I need to put the car in a special gear or neutral to get the line seated? Thanks in advance

 

If you have the trans with the 5 tubes, there should be 2 brackets that hold them in place. When installing the tubes , tap them lightly until fully seated.
If this was an overhaul, you would use a thread locker between the tube and case.
Some have the clamp that holds the reverse tube and trans oil filter in place.

 

Yes. I loosened the bracket, and checked the hole that the longer end goes into. It's all clear and a skinny screwdriver can travel as far as the tube needs to go. But when I insert it, it stops about half an inch too soon to seat properly. I tried twisting the metal tube while pushing it. Tapping it with a plastic mallet while twisting it, but it won't go all the way. I almost want to cut half an inch of tube off. Do I just need to keep at it? Nothing special for what gear I'm in, etc. But thank you for answering.

 

If they were in there previously, they should go back in there.Should not need to us any excessive force.
Exactly which tube is giving you the problem ?