You effect a change. Here the word effect precedes an impacting result. You caused change.
A change affects you. The word affect precedes a subject that was impacted. A change changed you.
Both affect and effect are about impact. The subtle difference is that one is for the impact itself. The other is about the thing impacted.
Lets mix them up:
If you say you affect a change then you're saying you changed a change.
If you say a change effects you then you're saying a change caused you to be.
Mnemonic: your parents got together one day and effected you. Later, when you learned how that works, you went, EEEEEW!