Report Setting not defaulting to custom report for some users

SOLVED

I've recently created some custom versions of reports (AR Aged Invoice Report, for example) and set them as default for all users, but for some users it still defaults to the STANDARD report every time. It is set to the default report via the checkbox on the report options screen and I've also looked in DFDM and changed the default setting to "Y" where it was "N" for some users. What am I missing?