Add new custom value in reasons combo box of opportunity close won

Hi,

Version: - 22.207.0013

i would like to add new custom value in reasons combo box of opportunity close won. 

I unable to add, can anyone give me suggestions for this modification.

I tried in this version 22.207.0013

I tried as field in the left-hand side, select the field reason click on Combo Box Values,

add new values but unable to do it.

I need to add custom value in reasons combo box of opportunity won/close.

I tried so many times solutions, but it is not working.

can anyone help me for this modification?

I would like to be able to add additional reasons for marking an opportunity as lost. Has anyone found a way to do this?

Thanks in advance.