You can manually upgrade or use the automatic option to upgrade to the latest firmware version. The firmware can be downloaded from the WD Support website.
It is possible to downgrade but it generally takes a little work via SSH to do so.
See the following link for more info on various firmware and how to downgrade. Note you cannot upgrade an older v4.x to newer v2.x same for v2.x, you cannot upgrade newer v2.x to older v4.x.
Thanks @Bennor, while preparing for updating I noticed that I don’t have access to view the contents of of my always connected My Book.
Logged into Dashboard as administrator
Windows 7 file explorer cannot view
I attempted to change access to Public which did not provide access - no change
Using Dashboard started the recovery process and discovered My Book 2 safepoints are selectable
Initiated a reboot on Dashboard and rechecked access using Windows explorer
I now have access, but when attempting to view the contents of _WDPROT results in a permission problem
I want to view a safepoint prior to updating firmware; what am I missing?
##update
I used the following procedure to successfully update my firmware from v04.01.03-421 to v04.04.03-113
made 2 copies of all data on My Cloud 1) USB3 My Book & 2) eSATA
ejected My Book and verified readability of contained data
rebooted My Cloud
updated firmware on line
confirmed all data was present
reconnected My Book
configured a new safepoint because safepoint that existed provided error message when I attempted to recover as a test.
The flaky permission problem connecting to My Book seems to have been solved by the firmware upgrade.
Access to contents seems to be faster now.
Update process took about 1 hour discounting the 2 data copies.
Update #2
After a new Safe Point creation response on Dashboard seems to be faster.
Extremely important - make a copy of your data prior to updating firmware