Before you allow users to update any data, you must display it on the screen.
Passing Data: Make sure to define the parameter on a page that holds a data of TypeRecord. Also, pass the parameter from the previous page. You can follow the instructions for passing the data from one page to another here.
To show data in the TextField widget:
Select the TextField Widget from the widget tree or from the canvas area.
Move to property editor and scroll down to the Initial Value property.
Click on the Set from Variable text. (This will open a new panel)
Find the Source dropdown, click on unset and select the source. For showing data from the Parameter, select the Parameter Name which holds the record.
Under the Available Options, click on Unset and select the field that you wish to show.
Pro tip: After adding the Update Record action, you can open the main Todo listing to show the updated item. You can do so by chaining/adding the Navigate To action by clicking on the + button inside the already added action box.
When you run the app, it should like the visual shown at the start of the section.