hermit crabs changing shells

Question
I have four hermit crabs and they look a like.  How will I know which one is which when they change shells?
P.S.- I know you can look at there skin and stuff but that still doesn't help me!

Answer
Emily,

I can tell by their personalities. But they usually don't all change at once so you will be able to tell which one has changed by looking to the bottom for vacated shells. if you remember where you put your shells you can look to see whose shell is in the place where the one your crab changed into was. Hope that last line made sense!!
-Katie