IT/Software/Video Applications/Kdenlive
General
This program has been ongoing for a very long time.
There are reasons for everything.
To learn the basics count on two hours to learn the controls.
The program is far more powerful and has a bigger engine than most users(myself included) will ever use.
Basics
Define your profile/project settings carefully.
Kdenlive has the tendency to upscale the project depending on the clips you import
That will later break rendering unless you have a 500 USD graphics card.
Yes of course the 500 USD is arbritrary and completely made up.
Who has time to research that kind of stuff.