linux – What's up with my $ PATH?

I'm trying to make my personal cmake installation the default option for my user by adding a directory to PATHbut I am confused and hope to get some help.

I am remotely connected to a Linux environment. If I type echo $0 I receive -tcsh output. All I find online indicates that the PATH variable in tcsh is separated by spaces, but if I type echo $PATH I get a list of directories separated by :. It's bash-like.

If I type PATH=foo, I receive Command not found. If I try instead set PATH = foo, I can echo $PATH and get foo. It's like tcsh.

If I type which cmake I receive /bin/cmake. If I use set PATH = foo add my personal cmake installation at the beginning of PATH, I've still /bin/cmake. this seems to be PATH is not used at all.

How can I get which cmake to find my installation, and what do I miss that makes the above so confusing for me?