Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The money, which you mentioned in your question, belongs to you and it is your property so you have to pay the Zakah of that money to needy and poor Muslims. But the person who holds it as a loan or a deposit is not responsible for paying its Zakah. You may appoint him to pay the Zakah on your behalf.
If a trustee cheats or does injustice to the one who has deposited the money to him then that money would be considered loan and then the rules of loans apply on it.
If the indebted person is wealthy and able to repay his loan then the owner is responsible to pay the Zakah of that loan every year.
If the indebted person is poor or he is a procrastinator then the owner should pay the Zakah of that money for only one year after the loan is repaid.
Allah knows best.