You do not report the amount of funds you have in a US bank account on a US federal tax return. You only report the amount of interest earned on those funds, if any, on a tax return and then only if your total income is above the minimum filing requirements.
Go to this IRS website for an interview on who needs to file a tax return - https://www.irs.gov/help/ita/do-i-need-to-file-a-tax-return
