Overview
Canvas Apps allows the ability to change the Authoring Version of the power apps maker. There are valid reasons for changing versions. Typically, it’s related to bug that might come up and you need to deploy new functionality without being on the recommended version. This will allow you to go to a previous version that’s still permitted to be used. Another reason why is to test the upcoming release that’s currently in preview.
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Change Authoring Version
In your Canvas App, go the Setting in the ribbon

Click Support on the left Nav. Here you will see the current Authoring Version. Click Edit

Select the dropdown for Authoring Version. Here you will see 2 or 3 previous version, the current recommended version and either 1 or 2 versions in preview.

Once the version is selected, click Reload + apply version

Once your app has reloaded, you will see the authoring version has changed.

