If you want to update your WordPress installation from your dashboard and WordPress is always asking for your ftp credentials, then you may have bad files ownership for your WordPress files.
To resolve this problem, connect to your server or wherever your wordpress installation is stored and
sudo chown www-data:www-data -R yourwordpressdirectory
In this case, www-data is the name of the owner of the files, i.e. your web server (Apache in this case).