In TC, the PS1 variable is exported from .profile, which is a login file. What this means is that the variable is set once, and then .profile is never read after that. The result is that no changes to that file affect your environment unless you run the file again (or log out and log back in). So before starting x, run the command source .profile (shorthand: . .profile) (shorter-hand:. .pr<tab>)
Alternative: set PS1 in .ashrc, which is read for every ash shell (TC base doesn't use bash)