Tif file association fix

I go online to & do a query, get the results, select & item for viewing, during the normal process a window opens up Security Warning "do u want to open-save-exit". The Problem: the program designated to open the file is not the correct one for the file type. i.e. "TIF" file. Right click does nothing to allow me to change to another program that supports a TIF file. The only way to view the TIF file is to save to a folder where I have set up the Folders via Settings/Control Panel/Folders to use Microsoft Office Document Imaging as the default for opening TIF files ONCE it is saved to the hard drive. The problem as stated above is in trying to open a TIF file from a web site before I save it. I know this site to be a trusted site. How do I change the association to a different program? After lots of queries on the internet I have come to the conclusion that I must modify the registry for file association and being a novice at this I don’t feel safe in taking this on.