Hi, welcome to the forum
Codeblocks is not a compiler, but an IDE, it can work with many different versions of compilers. For convenience we ship a compiler. For 17.12 it was probably gcc 4.5...
If you want some recent compiler you can download it for example from here
https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/installer/mingw-w64-install.exe Install the new compiler in some directory, and point codeblocks to it:
1) Start codeblocks
2) Settings -> Compiler ->Toolchain executables-> Compiler installation direcotry -> point it to the bin firectory of your new installation of the compiler
3) You may have to fix the executable names from the Program Files at the bottom
C compiler -> x86_64-w64-mingw32-gcc.exe
C++ compiler -> x86_64-w64-mingw32-g++.exe
linker for dynamic libs -> x86_64-w64-mingw32-g++.exe
Now if you also want to debug, you have to point also the debugger to the new version
Settings->Debugger->Default->Executable path-> Point it to the gdb.exe in the bin directory of the new installed compiler
Now if you want to use c++17 you can
1) create a new project.
2) Project->Build options->Select your project name on the left->Compiler flags-> Select the c++17 flag, or add "-std=c++17" in other compiler options
et voilĂ you have the newest compiler with your current codeblocks version
For your other questions... This is the wrong forum to ask.
We support only questions about codeblocks, and not about general c++ things
greetings