I went to Kvantum Manager and changed my theme to “KvCurvesLight” but It also couldn’t able to change my application menu. My pic will let you know the problem I am facing!
Welcome to the forum!
Kvantum Manager is only for theming Qt applications.
The GNOME Shell theme can affect the Application menu and Workspaces background, but not all do.
You’ll need to enable the User Themes GNOME Shell Extension in Extensions to be able to choose another GNOME Shell theme. Then open Tweaks and look under Appearance.
You might also like the Blur my Shell extension.
Thank You! One Problem Resolved!