For the simple script you can call it with the -x option as follows:
sh -x myscript.sh
If your script is complex (and calls multiple other scripts) then maybe this is appropriate:
alias sh='sh -x'
alias bash='bash -x'
alias /bin/sh='/bin/sh -x'
alias /bin/bash='/bin/bash -x'
./myscript.sh
Or if you really need control, and your subscript recreates its own shell environment
and won't listen to you, then whack it over the head with the following (use at your own risk,
be sure to put everything back where you got it from):