In the System Tools > Disks application, select whichever drive you want to enable write-through caching on, then at the top-right of the application you'll see a button with three vertical dots. Click that and select Drive Settings.
You can set Standby Time (I have mine set to 15 minutes), APM Level (I have mine set to 255. Keep in mind that rapid spin-down (enabled with APM <=127) can shorten drive life), Automatic Acoustic Management (I have mine set to Loud (Fast)... I haven't noticed any change in drive loudness) and Write Cache Settings (I have mine set to Enable Write Cache).
As the application states: "Performance is increased by enabling write caching, but leaves the system susceptible to data loss in the event of a power failure."... but on a laptop (which has a battery), your chances of experiencing a power failure before you can get the laptop shut down are slim. My laptop not only has the internal battery, but a live UPS with a battery bank that gives me three days of run-time, so the chances that I'll experience a power failure are slim-to-none.