"After I finished my income, and chose standard deduction, my federal refund amount didn't change at all. Not sure I understand why."

If you have no tax liability (a zero on line 11, Form 1040), then your refund amount won't change.

I have had the same issue several years running.  I have a simple senior return and after selecting standard deduction my return does not budge.  I have values in line 11.

The standard deduction is already factored in when you start the return.   If you had more itemized deductions than your standard deduction, you would see a change.  @haw5    On a 2024 tax return, your standard deduction (or your itemized deduction) is on line 12.

Standard Deduction vs Itemized Deductions