We are facing the same issue.
In our case our costumers aren't only elderly, but also have few experience using remote assistance tools.
QuickSupport with the proper UAC's interaction will solve 100% of our difficulties.
If we don't use QuickSupport, it's needed to install de full client and for that we need to use another remote assistance tool, because UAC pops up to ask about confirmation on install. The user who we are connecting doesn't know how to install it and enter registration key.
Also, full client by default starts in view mode and the user needs to switch to full control manually.