Changing api credentials

I recently changed payment providers and need to change my API credentials but am not having any luck. API credentials are for Authorize.net. Tried changing by both changing the source code (didn't work) and eCart Local Checkout under Server behaviors. Any ideas?

BTW - the attached file is of the a working version of the cart - don't know if that's unhelpful

It should just be there on the page on lines 315 and 318. Maybe the issue isn't with the credentials? Did you check the session dump after a failed transaction to see the failure message?

I tried changing the credentials on those lines but it only seemed to put the cart in testing mode, but I definitely turned off test mode on Authorize.net.
When I change the credentials in the server behaviors instead, I get a failed transaction.

Not entirely sure where to find the session dump. I found this code (<pre><?php var_dump($_SESSION); ?></pre>) somewhere in the forums and put it in but I don't see where the dump gets placed.

Try changing this line:
$AuthNet_required[0][$nextIndex] = "x_test_request";
$AuthNet_required[1][$nextIndex] = "".($WA_Authorize_Net_API_Credentials_TestMode) ."";

to:
$AuthNet_required[0][$nextIndex] = "x_test_request";
$AuthNet_required[1][$nextIndex] = "false";