This post will show you how to change how frequently your system checks for updates and ensure that you always have security updates installed as soon as they are available.
First you need to open software Sources which can be easily done by searching 'Software Sources' in the dash:
Next navigate to the 'updates' tab:
From the 'Automatically check for updates' drop-down menu select from: 'Daily', 'Every Two Days', 'Weekly', 'Every Fortnight', 'Never'.
From the 'When there are security updates' drop-down menu select 'Download and install automatically'
When prompted enter your password to confirm the changes.