How to adjust BGM volume with Unity button

Unity Engine
1

Questions about UI.
I want to increase or decrease the volume of BGM every time I click Button A or Button B (Button A increases by +0.05, Button B decreases by -0.05).
BGM is made by AudioSource as shown in the figure.
I want to control with On Click () of Button A and Button B. Can you tell me what to do?

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2

This is one of the first things covered in any Unity UI tutorial. Please work through a few of them and it will quickly become obvious what you need to do. Just google for “Unity UI button” or something.