Historical Linguistics and Language Families 1, Exercise 1: kinds of change

awful: "awe-inspiring" -> "very bad"   semantic change (pejoration)
RP losing /r/ in car                    sound (phonetic/phonological) change;
                                        the source gives social prestige as
                                        its cause
broadcast: seeds -> signals             semantic change (metaphor)

None of these is a syntactic change: syntax concerns sentence structure.