In box 1a and 1b I have the amount of $1523
The foreign tax paid at box 7 of $401
If I instead enter a zero amount in box 7, the federal tax is $37 less, this seems backwards
This could be because of your filing status. If you are filing with any other status than married filing jointly, you must fill out a Form 1116 to claim a foreign tax credit if the amount of foreign taxes paid is more than $300. If you don't do so, there is no credit for the foreign tax paid (I'm not quite sure why your tax liability increases when you enter it, but Form 1116 should fix it). Deductions and Credits/Estimates and Other Taxes Paid/Foreign Taxes.
This could be because of your filing status. If you are filing with any other status than married filing jointly, you must fill out a Form 1116 to claim a foreign tax credit if the amount of foreign taxes paid is more than $300. If you don't do so, there is no credit for the foreign tax paid (I'm not quite sure why your tax liability increases when you enter it, but Form 1116 should fix it). Deductions and Credits/Estimates and Other Taxes Paid/Foreign Taxes.