I have thought long about this and will now share it to the ZD forums! 
Throughout SS, Link meet the old Impa at the beginning to end. And she is always wearing the bracelet Zelda gave her back in the past,
and Zelda gives it to Impa after Link has taken the Master Sword in the pedestal. But Link still have to do all the hard work. How is this possible? Since Impa lived both in the past and SS present, she would have remembered something that didnt happen. It may be hard to understand what I am meaning, but I will try once more:
- Old Impa has bracelet
-Zelda has bracelet too! (the given one in the past)
- Old Impa has the bracelet without Link havent saved the world yet
- Link saves the world in the past, and put the Master Sword in the pedestal in past
- Zelda gives young Impa the freaking bracelet in the past
- When they get back to their own time, she has the bracelet all along
How is it possible!? If Impa had the bracelet all the time, the world should have been saved all along.
It is like Impa remember Link saved the world and Zelda gave her the bracelet, but it didnt happen even though she got it from Zelda!? It is so brain-twisting!
Does anyone have an explanation for this?

Throughout SS, Link meet the old Impa at the beginning to end. And she is always wearing the bracelet Zelda gave her back in the past,
and Zelda gives it to Impa after Link has taken the Master Sword in the pedestal. But Link still have to do all the hard work. How is this possible? Since Impa lived both in the past and SS present, she would have remembered something that didnt happen. It may be hard to understand what I am meaning, but I will try once more:
- Old Impa has bracelet
-Zelda has bracelet too! (the given one in the past)
- Old Impa has the bracelet without Link havent saved the world yet
- Link saves the world in the past, and put the Master Sword in the pedestal in past
- Zelda gives young Impa the freaking bracelet in the past
- When they get back to their own time, she has the bracelet all along
How is it possible!? If Impa had the bracelet all the time, the world should have been saved all along.
It is like Impa remember Link saved the world and Zelda gave her the bracelet, but it didnt happen even though she got it from Zelda!? It is so brain-twisting!
Does anyone have an explanation for this?