To get your investor password, go to "Tools" > "Options" on your MetaTrader 4/5 terminal, find "Change" > "Change investor (read only) password" under "Server" tab, then you can create a new investor password.
If you are trading with a mobile devices, simply follow the steps below:
【iOS devices】 go to "Settings" > the account tab on the top > the "..." icon under "Current Account" > "Change Password" > "Change Investor Password".
【Android devices】 click "≡" in the upper left-hand corner > "Manage accounts" > "Change password" > "Change investor password".