How to? Shared histories?

#1
Please forgive me if this is a stupid question, but due to my disabilities I'm somewhat stupid.

I use the TCC history (i.e., up arrows) a lot. I also generally have 4 or 5 (or even more) active TCC sessions going at any one time because I basically have a session for each "project" I am working on, and since I tend to do the same (or similar) things over and over in each "project", I use the up-arrow to repeat previous commands on a almost-constant basis. Well it used to be that each TCC session had its own unique history, whereas now there seems to be one shared history for all the currently active TCC sessions, completely obliterating the whole concept of a "project". So the questions: When/why/how did this change, and how can I get the previous behavior back?
 
#3
Thank you, Charles. I had a hard time finding it even after told me where it was because I'm half blind. The only mystery is how all of those "local" options got unchecked in the first place.