Pedrito,
Ah, well the good news is it is saving properly. More good news is that I think the problem is you are having is related to the string you are editing. If you are trying to change the string for the Self-enrolment method course welcome message, that string is in the component named Enrol_self.php, not in the component moodle.php. See some more explanation and the fix for that here: https://moodle.org/mod/forum/discuss.php?d=353997
Randy
Ah, well the good news is it is saving properly. More good news is that I think the problem is you are having is related to the string you are editing. If you are trying to change the string for the Self-enrolment method course welcome message, that string is in the component named Enrol_self.php, not in the component moodle.php. See some more explanation and the fix for that here: https://moodle.org/mod/forum/discuss.php?d=353997
Randy