I am using Tor Browser 4.5.3 and I have noticed that recently all the circuits created by Tor are geographically local. I am in Europe and now all circuits are constrained to that continent, while in the past they would range all over the World. Is this by design? How can I change it?
The EntryGuard (your first hop in a circuit) are static for an extended period of time and may appear relatively persistent. But the other two nodes should change randomly unless you have customized your Torrc file to choose a specific geographic region. Make sure that your Torrc file has not been customized. You may be using the same circuit repeatedly which is why you notice the same path so try restarting Tor Browser and see if it creates a new path for you.
It might be because there is a higher amount of tor relay nodes in europe when compared to rest of the world (It's very less in Asia afaik, correct me if i'm wrong). I myself often see all of my three nodes to be in Europe (Switzerland comes up a lot). You can check the relay information on tor's Atlas project, or TorStatus.
I hope this solves your problem. :P
Edit - You can also use Globe, a tor relays and brigdes explorer inspired from Atlas.