✔ 最佳答案
Firstly, I wanna to ask "Are you a HK permanent resident?", just turn over your old I/D card then you will have the answer.
If you are a HK permanent resident, you can go and change for the adult I/D once you come back to HK.
Don't affraid of the penalty ($5000) for the late, it will be waved since you were not in HK when it should be changed.