Create a copy of your old FMOD Studio project. (You could do it with the original if you wanted, but backups are good policy.)
Open the copy in the new version of FMOD Studio that you want to use. When prompted to migrate the project, so so.
Open the project you want to copy the events into as well, such that both projects are open at the same time, in the same instance of the new version of FMOD Studio, albeit in different windows.
In the migrated project, select the events and select “Edit > Copy” or hit “Ctrl+C.”
In the project you want to paste the events into, select “Edit > Paste” or hit “Ctrl+V.”