cmake switch to use gcc/clang failed and always use msvc compiler - c++

Question

I'm on win10 and I have installed: MSVS2022 with msc++ compiler, codeblocks with Mingwin-g++ compiler and then llvm clang.
I then installed latest cmake and have a very simple CMakeLists.txt in a directory named basic with some cc files:
cmake_minimum_required(VERSION 2.8)
project(my)
add_executable(my main.cc power.cc)
I do these commands in powershell:
mkdir build
cd build
cmake ../basic.
-- Building for: Visual Studio 17 2022
CMake Deprecation Warning at CMakeLists.txt:17 (cmake_minimum_required):
Compatibility with CMake < 2.8.12 will be removed from a future version of
CMake.
Update the VERSION argument <min> value or use a ...<max> suffix to tell
CMake that the project does not need compatibility with older versions.
-- The C compiler identification is MSVC 19.31.31104.0
-- The CXX compiler identification is MSVC 19.31.31104.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: d:/Program Files/Microsoft Visual Studio/2022/Community/VC/Tools/MSVC/14.31.31103/bin/H
But I wish I could use g++ or clang++, so I tried several methods at the same time.
(1) I changed CMakeLists.txt to add some lines:
set(CMAKE_C_COMPILER "clang")
set(CMAKE_CXX_COMPILER "clang++")
SET (CMAKE_C_COMPILER "d:\\Program Files\\LLVM\\bin\\clang.exe")
SET (CMAKE_C_FLAGS "-Wall -std=c99")
SET (CMAKE_C_FLAGS_DEBUG "-g")
SET (CMAKE_C_FLAGS_MINSIZEREL "-Os -DNDEBUG")
SET (CMAKE_C_FLAGS_RELEASE "-O4 -DNDEBUG")
SET (CMAKE_C_FLAGS_RELWITHDEBINFO "-O2 -g")
SET (CMAKE_CXX_COMPILER "d:\\Program Files\\LLVM\\bin\\clang++.exe")
SET (CMAKE_CXX_FLAGS "-Wall")
SET (CMAKE_CXX_FLAGS_DEBUG "-g")
SET (CMAKE_CXX_FLAGS_MINSIZEREL "-Os -DNDEBUG")
SET (CMAKE_CXX_FLAGS_RELEASE "-O4 -DNDEBUG")
SET (CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
cmake_minimum_required(VERSION 2.8)
project(my)
add_executable(my main.cc power.cc)
I cleaned the directory under build and run cmake again. Doesn't work, still choose msvc compiler.
Then I set environmental variable in Powershell like this:
$env:CC="d:\Program Files\LLVM\bin\clang.exe"
$env:CXX="d:\Program Files\LLVM\bin\clang++.exe"
I tried again. Doesn' work. Then I used the command line option:
cmake ..\basic\ -DCMAKE_CXX_COMPILER="d:\Program Files\LLVM\bin\clang++.exe"
Doesn't work. All methods tried together, still chooses msvc.
How to solve this problem?