How to preview a form
From the form designer's toolbar, click Preview to open a window that closely resembles how the form will appear on a device. If your form includes hidden fields, you can enable the Show Hidden Fields option to display them. This is especially useful for testing fields that are populated dynamically, such as those linked to a data set. For example, you can verify that a section and its hidden fields are functioning as expected.
Note: If your form uses data sets or form actions, live data may be triggered and updated during preview. In these cases, we recommend using the Preview window in a test environment.
In the following illustration the Make field is in a data set and is a hidden field but displays in the Preview Form window because the Show Hidden Fields toggle is on.

You can switch the preview mode to see how the form will appear on a tablet or phone. Keep in mind that phones span two columns, tablets span three columns and a desktop spans four columns in Preview mode. Additionally, you can type or select values to test calculated fields and confirm that each input uses the correct input type.
Click OK to close the Preview Form window.