PowerApps Pro Tips | Using Variables. Like parameters, variables are very helpful, and can be used to increase user communication in your app. A variable in Microsoft PowerApps is used with the function UpdateContext. Below are a few ways you can start using variables immediately in your apps. User Communication. In a scenario where youâre sending data back to a source and doing a Patch, at times the user can be confused about whatâs happening (if anything is going on at all).