*Warning*: Cannot modify header information - headers already sent by (output started at /wp-settings.php:###) in /wp-includes/pluggable.php on line ###
With this error message it is stating that there are some white spaces in the php file that the output was already started on.
To fix this you will need to find the location that is causing the error.

Find the header() statement that is causing the problem, use the ### line indicators to help locate.
This will either be before or at this line mentioned.

Look for any statements that could send output before this header statement.
If you find one or more, find some way to move the header statement before them.
Complex conditional statements may complicate the issue, but they may also help solve the problem.
Consider a conditional expression at the top of the PHP script that determines the header value as early as possible and sets it there.

Look at the error and check the Line ### that the error is occurring on.
If the line is blank and either before <? or after a ?> tag, delete all blank lines that appear in this location.
Load your site after this change is made and it will load correctly or you will need to repeat process until all blank lines causing the issue are removed.