Can multiple Final Cut Pro transitions can be inserted all at the same time on a MacBook Pro?

Select the clips the timeline, find the transition, double click it.

Or Cmd-T for the default transition.

If you select multiple clips and double-click on one transition, that transition will be applied to all these clips' edit points.

The default transition is a Cross-dissolve but you can change it to any other type you wish.

Open the transition browser, command or right click the transition of your choice and click Make Default in the window that opens.

@D-Rob1, here are a few of the free, go-to tutorials to get you started and help speed up your FCP learning.

Steve at Ripple Training’s 60 minute FCP tutorial overview https://www.youtube.com/watch?v=HqUP7Zgeuck

Final Cut Bro getting started  https://youtu.be/L3bZ-ETKZ8U

FCP FTW: https://youtu.be/bNsJxKN_4z0?list=PLk1S35P86TzPmcjybsLUcmDmbbyzsMa4A

Izzy Video tutorials. Older so the UI looks different but the concepts are still correct. https://youtu.be/_jvyrnQpR1E?list=PLp5SAgbM8S87n1qvv34-PAU2zMHLlXyfb

Just had a gander at the Final Cut Bro tutorial and was very impressed with the amount of content squeezed into half an hour though beginners would be well advised to get a copy on their computer as they will need to do a lot of pausing and rewinding!

I hate to think what it's done to my blood pressure.

Thanks for the link terryb, it was new to me.

You're very welcome Ian. Dylan was one of the keynote speakers at the FCP Summit last year and I think does a good job of explaining FCP concepts and techniques. He's also got a bunch of Motion tutorials.