This can be found through the Festinger Vault plugin while you edit the code.
WP dashboard → Plugins → Plugin Editor
Wp-config.php is one of the most important WordPress files because it contains your base configuration details. You’ll find it in the root of your WordPress file directory.
To edit the memory limit and upload limit, look for this line:
This limit can be changed from your WP-Config.
Modify the second parameter by increasing it. As I mentioned a PHP memory limit of 128M should be more than enough.
Save the file and you’re done. You may need to increase it again if you’re still getting the fatal error, but don’t go overboard or you may crash your server. All the more reason to reach out to your host for help.