Mainnet account username URL: https://www.bybit.nl/app/user/security
Testnet account username URL: https://testnet.bybit.nl/app/user/security
To check your account UID,
Method 1: Click on the link above to enter your account's settings page. Perform a login if prompted. And you will be able to see your UID here.
Method 2: From the top right corner of any Bybit (powered by SATOS) webpage, navigate your cursor to the “Profile” icon, and you will be able to see your UID from the dropdown menu.
You have successfully located your account UID!