Incorrect options for CLion at Build time when using CMakePresets

When using CLion on coding CMake project, I use CMakePreset to configure project.

I set some command in CMakePresets, such as 

“buildPresets”:[

{
     "name": "build-debug",
     "configurePreset": "debug",
     "configuration": "Debug",
     "jobs": 3,
     "verbose": true
   }]

in this json code, i set cmake to use 3 thread to build my project. 

but when I using CLion to  Building the project, the build info show that it still using 6thread to build. such as this.

====================[ Build | demo | debug ]==========================
/usr/bin/cmake --build /home/sumover/CLionProjects/demo/build-debug --target demo  -- -j 6

is this an error, or there are some way to configure it. thanks  :)