You can turn off "Managed Mode" and work the way you did in X16. Under "Preferences" > "Project Management" de-select "Use Chief Architect Project Management".
If you are using "Chief Architect Project Management" Chief is going to manage your files for you. It's going to be a lot more difficult to store files on Dropbox and still work on them. You might want to consider turning "Project Management" off to store files on Dropbox.
My 3D Connections configuration file for X15 is attached below if it is of any assistance to you. I think one can use the file to import the radial menus I created and link to buttons on their 3D connections device.
Chief X15.zip
ComputerMaster86's post in X17--Can I save my plan and layout to dropbox? was marked as the answer