Invoke queuing when queue doesn't occur

I'm copying files from three ISOs and the copy operation wasn't queued (all three copy operations are happening at once). Is there a way to invoke queue on the currently non-queued copy operations? Thanks. (Usually queue just happens automatically and the setting I see in preferences bear that out.)

See Copy Queues in the manual for a description of the rules for automatic queuing, as well as how to manually queue things if needed.