I'm using macXvideo. I have absolutely no experience of editing videos. Yet I know how to edit videos with this program. Amazing! I just load my video to it, there are well-marked options for cutting, cropping, adding effect, adding subtitles, rotating, merging etc. Merely choose the target option, like Ariadne's thread, to finish video editing fast. Frankly, it's more fundamental, but you shouldn't require more for free ones. For me, it works fine to edit hd, 4k videos for YouTube, Instagram, and Facebook. Grab the tool here: https://www.macxdvd.com/macxvideo/
Yep, very nice for the first timer, both the video quality and footage edit. Em, I'd like to make the transition a little bit more natural, lol. Which editing tool did you use? macXvideo may be a better choice for beginners.
What's the specific GPU of your laptop? As you have a 16GB RAM, if your GPU is built with hardware acceleration technology, like 4th-gen Intel® Core™ processor, NVIDIA GeForce 970, you can use macXvideo to edit your 4K UHD videos. If not, this free editing software is up to edit 1080p/720p videos flawlessly. Here is it. https://www.macxdvd.com/macxvideo/
macXvideo could do that, for cutting, cropping, merging, rotating, color grading, adding subtitles etc. Better yet, you don't have to pay any money. Check the free software here https://www.macxdvd.com/macxvideo/