To set an existing author to a 'Layout Designer'

Once you have the ‘Layout view’ feature enabled, any user who has the ‘User role’ of ‘Layout designer’ will be able to access the feature, your account ‘Administrator’ will be able to configure this.

Once you have logged in as an ‘Administrator’, open the ‘Authors’ page by clicking ‘Your account’ and then ‘Authors’.

Press the name of the Author which is highlighted in blue:

This will open the ‘Edit an Author’ menu, click this menu:

…and then choose ‘Layout designer’:

…and press ‘Save changes’.