Username or EmailPassword
Swipe left, type "settings" in to the search field. Unless the user has gone in and specifically turned off indexing (it's on by default) a few milliseconds later - you will have the settings app listed. Top tip, probably verging on power user, but well worth remembering.
That might have been her next step if we hadn't found it (buried in a folder labeled "Useless Stuff", by the way!), but I have never had more than a handful of apps on an iDevice so it never even occurred to me.
I use it more on my iPad, as that has 64GB of storage, and it's much easier to install an app and misplace it. On my Phone, I tend to delete stuff I don't use and only reinstall when needed. I also don't put settings in a folder marked "useless stuff".. ;-)