Sorry to take so long to get back to you DT.
I worked out that it was more cost effective to buy a new theme than spend my limited time trying to work out why Filezilla won’t work.
My Filezilla fail? The reason, I think, is that FileZilla may not have liked my Mac and I being on a network at home, that i.e. not connected directly to the internet - I could update via my partner’s PC but I was not keen on bothering him for something I should be able to sort out. I got frustrated at spending valuable ‘making’ time struggling with sorting it out and having to pester technical people who have better things to do.
I am sure Filezilla is a real asset to many, and the failure is my own!