Am designated trustee of my mom,part of her trust is her bank account.I have discovered that 1) the beneficiary of her account is solely under my name 2) the bank was not notified by my mom that the acct is mentioned in the trust-will my being the sole beneficiary of her account as per bank records be over ruled by the trust as the bank was not notified by my mom ?( the trust has my 2 siblings and myself as benefciary)

The Bank probably isn't going to agree but the Trust rules. My guess would be that the Bank will say their rules prevail and in the event of a death they will freeze the account upon notification of the trust.

I assume your mother is still alive? If so she needs to advise the Bank of the trust document.

The wording in the trust may very well cover this situation.