Let's go through the process:

> Tap the 3 horizontal lines on the MetaTrader application. 

> Tap on Manage Accounts

> Tap on the Account Settings icon.

> Tap on Change Password.

Choose Change Master Password in the first selection box.

>  In the second selection box, enter your Current Master Password.

>  In the third and fourth selection box, enter your New Master Password.

>  Tap on Next to continue.

>  Tap on OK once the finalization box appears.