Can someone explain me step by step how to upgrade from Cubase 7 to Cubase 8 Pro?
Go to the Steinberg site
Choose Update from 7 or 7.5
Choose download
Download from the link given
Install
You don’t have to uninstall 7.5.
The update will pick up your preferences. However it might be a good idea to trash them and start again in 8 as many of us have had issues when importing projects - mostly minor stuff. You might want to locate where the mixer and insert presets are kept and import them by placing them in the corresponding folders in the event - however they should be updated too.
Good luck