Sometimes in your apps, you have to make changes. For example, you may remove columns from a Google Sheets sheet that is connected to a recipe, or adding a Salesforce custom field to one of your objects. In order to be able to see these newly added/removed fields into existing recipes which use them, you will need to refresh schema. This will need to be done every time there are changes made to your app's interface (eg. new fields or removed fields, not data within the fields)
To refresh schema, make sure your recipe is stopped by clicking "Stop Recipe", scroll down your recipe to look for a sentence on the bottom right corner of your recipe, and click on refresh.
Alternatively, you can press the combination keyboard keys "r" and "f" to refresh schema for the recipe.
In some recipes, you will not be able to see the refresh schema option. This will occur if the actions you are working with do no contain any fields that can be modified in the apps.