Starting Sage X3 v7 you should go to Administration -> Authoring -> Home pages, find your Landing Page and assign to Roles of your choise.
Roles list is blank for personal pages, which then are available only to Owner himself.
No need to change the Owner after assigning Role(s), but you can.

P.S. You might reconsider your Roles set because of different Personalisation levels, Landing pages and navigation pages distribution between user groups.