Many thanks to Biggles, Erato, Talacharn and KGarrard for your advice, I do agree that synching with an online database is generally something that should be avoided.
However, I do a lot of work on the Familysearch family tree and the reason I need to link to it is to periodically download Gedcom data for that part of the tree I have worked on - before it is modified by someone else. So the synching of data between my PC's tree & the Familysearch tree does not really occur - I just download a new & dated Gedcom file whenever I want, for my records.
That being said, I do need to visualise and query these records from time to time and this is the reason I bought commercial software.
Being retired, a subscription type service or expensive, cutting edge software is not something I need or wish to take on.
I have checked out the Ancestral Quest software and this seems to be inexpensive, easy to use and to do what I want, without drama.
Of course the AQ interface is quite dated, but for me this is a plus, because both me and my hardware/software setup are also quite dated. It doesn't have all of the bells and whistles that the other, more expensive genealogy software offers, but it seems to be tried, tested and reliable.
To conclude, when I open the Rootsmagic app today, I find the blue/green interface to be both unfriendly and unhelpful and, bearing in mind the functionality problems I've had with it, I will not be using this product in the future.
Best regards