If you right-click on your topic and select properties (when in the library), you should see a properties pane open up on the right side of the UPK Developer. Under the General section, you will see the resolution that the topic was recorded at. Note that you will only be able to modify Module and Section resolutions - but not topics!
There seems to be a fix for DPI issues for 11.1 - you can grab this by logging into MyOracleSupport to see if that will allow your clients to view the UPK content that was created.
Unfortunately once a topic is recorded, there is no way to modify the resolution. I do however have a sneaky suspicion that that you will be able to use the Record It! client (available to UPK 11.1) in a multi-user environment. I haven't played with it much yet, but I seem to recall an option to modify the resolution of a topic within it using the properties pane. Perhaps you could give it a shot and see?