For a long time, the only way to retrieve your flashed scores was to recover your UID.
The UID is a unique account identifier consisting of 31 or 36 characters, including numbers, letters, and hyphens:
xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxx
e.g.: 7f5c2a1a-b8ed-4080-b833-e220357
XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
e.g.: B8151607-B325-4411-B154-C2E21A27E25C
The UID allows you to retrieve your flashed scores, account settings, etc.
As of today, there is no longer any way to retrieve the UID on the latest app versions, but here are the old tutorials:
Please log in to update your UID.
The UID is the string of characters after ?uid=
The UID is the string of characters after ?uid=
The UID is the string of characters after ?uid=