How can i upgrade the kernel?
Actually, kernels are an “exception” to the above rule, in the sense that they will only update to the latest patch version.
This is because Manjaro allows users to have multiple kernels installed. As such, updating your system will also update your installed kernels to their respective latest patch, but will not install newer versions nor uninstall older ones.
Please refer to the following guide for managing your kernels: Manjaro Kernels - Manjaro