Hello @lakyyzx and welcome to the forum 
I’ve added the android and how-to-use tags to your topic title.
Note: I don’t use krita on android so there may be some aspects of it that I don’t know about.
Looking at your video recording raises some questions and some points, as follows:
Which version of krita are you using?
I ask about the version number because you have a drop-down selector for the interpolation curve shape but I have separate buttons.
That may be an android thing, I don’t know.
Which theme and which style are you using?
(The theme and style are selected in Settings -> Themes and in Settings -> Styles.)
I ask because the theme/style can affect the presented colour of a UI element and some themes/style make it difficult to see some colour changes that happen.
e.g. It looks like your control points turn black when selected but I’m used to them turning white.
Some immediate advice I can give you is that if two control parameters have the same value, i.e. their control handles are on top of each other then it’s difficult or impossible to select a control point.
This happens with Scale-X/Y, Shear-X/Y and Rotation-X/Y/Z because they start off at the same values, i.e. 1.0, 0.0 and 0.0.
The way to deal with that is to turn off the visibility of some of the parameters by using the eye icon on the left. That makes everything a lot easier and more clear.
I usually turn off Shear-X/Y, Scale-X/Y and Rotation-X/Y, unless I’m using them.
Now for the Bezier curve interpolation:
Every time I use Bezier curve interpolation, I have to relearn how to do it because it is quite complicated in terms of all the options there are for selections.
However, it does work for me with krita on linux:
You should be able to have a single control point set to Bezier interpolation but you can also select more than one control point before clicking for Bezier interpolation.
There is another user who recently had these problems on android:
I’ll ping @Drawpile (a developer) to see if he knows anything about this.
In the meantime, please give answers to the question I asked earlier.