Audio mute problem pls Help!!

Cubase 9. When i use X to mute a section of a vocal track , cubase still play the section that i have muted on that same track, that i don’t want to hear.

You probably have multiple takes (layers) on top of each other? With ‘X’ you only mute the visible part on top. Make your lanes visible to see all the layered parts on this track and mute these as well.