Now, Yosemite update is not being shown to you because Apple hasn't updated the Software Update utility. The latest version is absolutely 10.10.2.
I downloaded it directly from Apple, as I have an Apple Developer account, where you can find it here:
Mac Dev Center - Apple Developer
There are instructions there on what to do if you do not have an Apple Developer account.
Apple also has new Canon software version 3.1 for the Mac available to the general public, which sounds a lot newer than what you have. There's no reason for you to stick to "Print Studio 1.3.6"