Why di login details for my Deriv MT5 dey different from di login details for my Deriv account?

If you never verify your account, you fit update these personal information for your profile, under the “About you” section:

See di difference:

Your Deriv login dey give you access to your main Deriv account dashboard, deposits and withdrawals, and options trading platforms like Deriv Trader and Deriv Bot.
Your Deriv MT5 login na specifically for you to access di MT5 platform and manage your trades dia.

For your profile, you fit also check the status of these things and update dem: