Control customization is really important for you to understand, because not all player feels comfortable to the default control. Some player play on small screen smart phone which make them feels abit struggle during playing.
These 3 steps below will help you getting better or comfortable after customization your own control:
1.Tap on tools icon on the top right welcome screen.
2. Tap on control tab
There are 3 methods for you to choose and test it, but if you still not like it you can click on customize tab.
3. Start customize
The picture below show how my customize change before and after
As you can see my ui become much smaller and als movement control. The shoot button and scope botton become bigger. This is just my personal preference. You can customize your in other to get comfortable with.