The details are in Form 1116.
Basically
Your foreign tax credit cannot be more than your total U.S. tax liability multiplied by a fraction. The numerator of the fraction is your taxable income from sources outside the United States. The denominator is your total taxable income from U.S. and foreign sources.
So be sure you have entered the proper amount not only of foreign taxes, but also foreign income (typically dividends) on your 1099-Ds. Sometimes you have to hunt for that information, other brokers make it obvious. Check to make sure it imported correctly.
Also I would recommend seeing if deducting your foreign taxes on Schedule A results in a lower tax liability. (I always suggest doing it both ways and choosing the more advantageous way). The 1099-DIV TT form has a checkbox for which you want to do (link to 1116 or deduct on schedule A). I believe you must do all or nothing so be consistent among your 1099-D's.
See https://www.irs.gov/individuals/international-taxpayers/foreign-tax-credit-how-to-figure-the-credit
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