I know that there are situations I can use either simple past and present perfect.
I changed my mind. I can go out with you for dinner tonight.
-> This sentence focuses that the change happened at some time in the past
I have changed my mind. I can go out with you for dinner tonight.
-> This sentence focuses on the present consequence, that is now my mind is different and I have a new decision now.
I have another example:
One of my mother’s friend haven’t seen me for 5 years. Today, she comes to my house and meets me, she will say:
You (have changed)/(changed) a lot, Jane. Now you are a pretty lady.
I know that we use present perfect for a past action has consequence on the present. Here the change happened in the past, the consequence in the present is that now I am a pretty lady. So that the present perfect is a good choice here.
But I am still wonder if the simple past is still fine to use here? Because I just want put the focus on a past action.