I personally use Premiere Pro by Adobe to edit all of my videos for work and for personal projects. It a fairly cheap and easy software to use unfortunately you cannot buy it outright but you can get full access to it for $ USD a month. If you do moreplicated and in depth YouTube videos with graphics and audio effects a must-have is Photoshop Audition and After Effects all created by Adobe. You can get access to the whole Suite of Adobe software for $ USD per month. If you are regularly editing large productions it a very much worthwhile investment. If you are just starting out and are testing the waters for making YouTube videos here are some options If you are editing on Mac OS with a Macbook or any kind of iMac the editing software iMoviees free with any MacOSputer. You can have multiple audio and video tracks some built in effects and transitions and the ability to place on screen. It great for getting the feel of editing but once you start to put together moreplex videos it gets a little limited. If you see it as a worthwhile investment the step up from iMovie is Final Cut Pro X a $299 USD editing software specific to Apple products. It very powerful and allows you to do much more advanced edits with a full color grading suite the ability to import transitions and graphics create videos with custom resolutions and much much more. If you are editing on Windows a great free option is DaVinci Resolve. There is a Studio version that costs $299 USD however the free version is more than enough for basic video editing. The color grading suite is one of the best in the industry and it a very simple yet effective layout with the ability to edit resolutions up to 8K. Hope this helps if you have any more questions feel free to drop them below and Ill see what I can do.