The default behavior of mpterm on startup is to run a bash shell. It is possible to override the default behavior in two ways. The first is to specify the --execute Command Line Option. The second is to add another shell, for example tcsh, to the list of applications in the Menu Page of the in the Preferences Dialog. The first shell in the menu list is the one that mpterm treats as the default. For example, to replace bash with tcsh as the default shell, simply make sure that tcsh replaces, or is above, bash in the list of applications.
At present mpterm recognizes the following list as shell commands: bash, tcsh, csh, ash, zsh, pdksh.