When I got my ywg he went through the overflow. I found him in the filter sock, alive. I put him back in the tank and I was thinking I need to do something about the overflow, right then he went back over. I retrieved him again and the overflow issue has been fixed.
I also have a Yasha goby and a pistol shrimp. The ywg sometimes stays in the same hole, all three together. Most of the time it's just Yasha goby with the pistol.
The ywg does swim around and acts weird like he's unhappy with the tank. I thought my ywg lost a few brain cells after going into the filter socks but I guess not as you guys report your ywg swims around also. I was serious thinking I had a nutty ywg. LOL