I just added a block of code (found here) to functions.php, crossed my fingers and clicked Update. Nothing broke. The changes worked perfectly.
Then I changed a portion of the code that outputs text to the page. No code was changed, only text. I clicked the Update button again and got this error message:
Warning: Cannot modify header information - headers already sent by (output started at /hermes/waloraweb035/b2427/pow.ccrbernie/htdocs/ccr/wp-content/themes/live-music/functions.php:16) in /hermes/waloraweb035/b2427/pow.ccrbernie/htdocs/ccr/wp-includes/pluggable.php on line 881
But the site still works, and the text changes I made were saved. I clicked the Back button and then clicked on the functions.php link in the right sidebar, to reload the file. Then made further text changes and clicked Update and still get this error message. But the new text changes were saved and the site still works.
Any idea what is happening and, more importantly, how can I fix it?