Did the distance between the uneven bars ever change?

Answer 1

They are different distances apart so the gymnasts can their tricks! For example, they stand up on the low bar, then jump to the high bar and swing on it. They wouldn't be able to do that if they were the parallel.

Answer 2

Yes it can be slightly adjusted for each gymnast but there are restrictions as to how much. Russian gymnast Svetlana Khorkina often competed with the bars as far apart as allowed due to her tall height.