List Update

After i add an int to an list but i update the int on the list will still be the same

When you add an int (or any Value Type for that matter) to a list, you copy it to the list.

So modifying the value later won’t update the value in the List. You’ll have to keep a reference to the index and update it.
If you handle Lists of Reference Types, it’s different. The List only contains a reference to the object.