Hi
I am on macbook El Capitan, 64bit. Cubase artist 7. Reason 8.3.
Cant rewire because Cubase seems to be installed as 32 bit version. Reason 8.3 is 64bit without option to open as 32 bit. 
So I am going to uninstall Cubase and reinstall as 64 bit. (I think I can do that).
Will I be able to open tunes that were created in 32bit Cubase in a 64bit Cubase?
Thanx.
EDIT: I think this answers my question: Cubase 6 101: Quick Start - 5 Running Cubase in 32 or 64 Bit - YouTube
Hi,
1st of all, you don’t need to reinstal your Cubase. Go to the Application folder, select Cubase application, Cmd+I to open Get Info. There is a checkbox to open the application in the 32bit mode. Disable it. Now Cubase starts in 64bit mode.
Yes, you will be able to open the projects, you created in 32bit Cubase. 3rd party-plug-ins might not open, if they are not bridged (internal 32/64bit VST Bridge).
Luckyly, you can switch back to 32bit any time very fast, if you need to for some project. 
Thank you Martin. Strangely for me, when I untick the 32bit option in Get Info, it remains as 32bit when I open the software. I assume then that I have chosen to install it originally as 32bit?
EDIT - Wrong, it is now showing up as 64bit. Strange, it did not do it immediately. All good.