The manual is not clear on this, they appear to confuse screens and tiles. On the Home screen you can only rearrange the tiles by touching, holding and move around - like your smart phone.
When on the Home screen and swipe to the next screen - at that point you can rearrange the functions shown by touching a function, holding and editing as desired (delete / add etc)
At that point touch the pencil / write symbol - this enables the creation of additional screens by touching the + symbol - a bit like creating shortcuts on the IS drop down menu.
I personally have four screens including the Home screen, you will find though that some if not all functions cannot be placed on multiple screens (that needs confirmation)
Initially, I had trouble setting up myself as primary user and using S-PIN, I reset / deleted everything and eventually got it right and works fine since then.
The software in my case and so many others was certainly infuriating - for over a year had to put up with errors appearing almost daily, the recent 1896 and IS software update fixed all that and although very late in the day, am now reasonably happy with the car