Can someone please explain me when should I use (and what is the difference) between the following sentences:

She told me.

She has told me.

They told me.

They have told me.

The new code caused this problem in the software.

The new code has caused this problem in the software.

The administrator created a new user account for me.

The administrator has created a new user account for me

Please give some examples/explanation from regular sentences (please no tenses explanation like past-perfect and past-simple and etc.. since I really don't understand them even in my own language)

Thanks a lot.
They have the same intent. 'Caused' is a simple statement of the past event. 'Has caused' tells us that the past event is recent or is important to the discussion now.
Students: We have free audio pronunciation exercises.
so if i'm having a conversation with a friend of mine about cellular phones
and I want to tell them about the new Apple Iphone that has been released yesterday
I would say "Apples has released their new Iphone yesterday" rather than "Apples released their new Iphone yesterday", because it is
either recent and important to the discussion now?
'With a specific past reference ("yesterday"), you cannot use present perfect; you must use past.
I think I understand now.

Thanks again for your help :-)
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