With the barrage of updates lately to fix UCE, program crashing etc,  can somebody explain the different ways to update the program and the function they do ?

On the menu bar on top, there is an Update button. A sub menu is Refresh Updates. What does it actually do ?  Does it uninstall a previous update and reload a new update ?

There is also a "Tools- repair update"  found on the computer program list menu under proseries 20.  What does it do different than Refresh updates ?  On one of the program crashes yesterday,  we were prompted to do this Tools-repair update.  Did not fix the crashing problem.

Knowing how the program works will make us better users.  Thanks for the upcoming explanation