I still do not understand crew training.

Steel_chaos, on Jan 02 2013 - 06:20, said: I have read and read and read the posts on this topic and I still do not understand how crew training works.
Let me start by explaining that I am grinding all nations and all branches of all trees, so I have a lot of work ahead of me.
I have in general worked my way from tier 1 to tier 2, sold the tier 1 and then worked on the tier 3.  At which point I sell the tier 2 and buy the tier 3.
There have been a few exceptions, but that's generally how I proceed.
I do not have unlimited garages or barracks but I have bought some extras of both.
It seemed to me that to save space and cost, I would train my crews close to 100%,  then move my crew from, for example, the BT-2 to the BT-7.
I understand that there will be a drop in skill when you move up, so I am OK with all this so far.
Here's where I am getting confused.
I was able to turn my Hellcat elite and the crew was 100% plus.
I bought a T26/2 and to save space in barracks I bought it without the crew.
I figured I'd just move my Hellcat crew into it and train them up.
I liked the Hellcat so I decided to keep it. I thought i'd just move the crew back and forth from the T25/2 to the Hellcat.
However when I put them back into the Hellcat, they no longer appear to be qualified to run the Hellcat.
I don't see any place that shows that a crew is qualified for multiple tanks (Yes I know must be same country and same type I.e mediums).
So what am I doing wrong?  What am I missing?
I am so confused.  Where did my 100% trained Hellcat crew go?