If you are a viewer on a dataset, variables you create in Crunch will be personal – available only to you. These variables will appear in the My Variables folder at the top of the variable tree.
Dataset editors can choose to make any variable available to all users on the dataset. When creating a variable, an editor will see the Personal/Shared toggle in the upper right:
Set the toggle to Shared to make it available to all users. Set it to Personal to make it available only to you.
You can change whether a variable is personal or shared in Variable Properties.