Kinemaster is the best. If you'll ask people what they think is the best video editor for an Android phone I'm pretty sure they'll answer Kinemaster too. There are certain features that you can't find in some video editing apps that are only found in Kinemaster that makes you edit videos like you are editing in Sony Vegas Pro. Chroma Key is an example. Do you want to add cool special effects to your videos? It's better if you'll use greenscreen edits. But how? That is where the Chroma Key feature pops in. Just look at how cool it is.
It's confusing at first but like everyone says, you'll get used to it. Here is a tutorial video:
To get rid of the watermark or just simply get access to these cool features and to be able to post, you'll have to buy it. But of course, who wants to pay when we can get those for free? Here is a video for that:
If this doesn't work for you, you can always search on Google or YouTube. If you want to make your videos look like it's professionally edited. Then you should practice editing videos using Kinemaster.