Call history

The phone will only save 100 calls. As new ones come in, the old ones get deleted. If you need to see older calls, you will need to access your phone account online with your carrier’s web site.

Not sure what you mean that she doesn’t have a problem. The phone will save the most recent 100 calls. Depending on how many calls you get each day, that will determine how many days are saved.

Glad I could try. You can always send feedback to Apple about this. https://www.apple.com/feedback/

There is nothing you can do to have it save more than 100 calls. As I said, it depends on how many calls a person gets each day that will determine how long the older calls are available.