I cannot seem to find where to change Correlation Tokens

Question

Hey there! I am currently working on a workflow for work and when I go to publish it an error arrive when validating the work flow.

(0, 0) Activity 'ID1' validation failed: Activity 'ID1' does not have CorrelationToken property set)

During all of my preliminary "how to make a kick butt work flow" research I NEVER came across anything about correlation tokens. But after the fact it turns out they are immensly important. Cool. Now I need to know how to go back through my tasks and whatever else needs to be changed to get my token scheme on point. But now I can't find any information on how to change the token. I'm using sharepoint designer 2013 but a 2010 work flow (I needed the "collect data" function). I have a few hours already in this workflow, if I must scrap it that's ok but I would much rather just go back through and change the correlation tokens.

Thanks in advance!

-Eli