If you have filed a 2019 tax return and need to change or add your direct deposit information, see this IRS website - https://www.irs.gov/newsroom/economic-impact-payments-what-you-need-to-know
The IRS does not have my direct deposit information. What can I do?
In the coming weeks, Treasury plans to develop a web-based portal for individuals to provide their banking information to the IRS online, so that individuals can receive payments immediately as opposed to checks in the mail.

When contacting the IRS website, it will direct you back to contact your tax preparer. There is no way to updat your bank information, until next year.