Problem with guitar level

Hello!
First of all I'm very happy with my VL touch!)
But there is one problem that I want to ask about.
I think there is a little bug with guitar level. Please, do the next steps and write if you have is also.

Use earphones to listen! And plug the guitar to VL.
1. Set guitar level to 20 and play a little to get used to that level.
2. Turn off VL touch.
3. Turn on.
4. Try to play again.
The level will be at 20, but it sounds as it is at maximum 25
5. Try to change at least to 21 and back to 20. Then you will hear that it went down and is correct.

Do you understand what I mean?
Thank you in advance!