I'm starting to feel like a broken record saying this, but there are of course multiple ways to achieve this in QlikView. One method, and probably the most commonly used, would be to define the variables in a QlikView script file as follows:
SET vQVDPath = C:\QlikView\Data\QVDs\;
The script file can then be included in multiple QVWs by added the following line towards the start of each script:
$(Include=..\config\variables.qvs);