adding transitions in iMovie

I have used iMovie for years although admittedly not recently. In fact, there have been several updates and perhaps a new iMac since I last used it. Adding transitions was a very easy operation in the old days. I have just spent a frustrating hour simply trying to insert cross dissolves. I have turned off the automatic option. I attempt to select clips, select transition I want and add it but this does not happen. Where I've managed to a actually add a transition (I'm not sure how this even happened), I've tried selecting the successful transition, copying it and pasting it into where I'd like a new one. Nothing works. Apple is becoming less and less logical, less user friendly. Can someone fill me in on what I'm missing here in this very simple operation.