Clicks occur during sound level adjustment

I think this is because the level change should only occur when the sound amplitude passes through 0-but in reality this is not the case

How can I fix this?

I was trying to implement an audio attack control

But it works with clicks-because of the problem of going through 0 sound level

Any idea how to fix this?

If there was a system behavior for the FADE IN sound,it would probably work as expected

, but it doesn't exist