Yes, it would also help for you not to assume straight off that I'm as thick as two short planks. I have seen that post, and it didn't help me - which is why I asked my question.
However, I certainly AM guilty of not making myself clear, so I'll put my hands up to that.
When I run a search, I am presented with five results. The top of the page says "Results 1-5 of 30". I click "Next" to see the next five. I am then told "Sorry, your search returned no results". There is, indeed, a "&howMany=" section in the address field - but adding 50 to it simply results in my being told "Sorry, your search returned no results". After all, 10x0=0, right? On clicking "Back" to go to the five I COULD see, there is no "&howMany=" in the address field. Adding one on, or copying the whole line of search commands to use from scratch, just gives me a blank page.
What I was asking was whether there is any way of telling the site BEFORE I make the first search how many files I want it to display at once - until they manage to fix what appears to be a glitch in the search engine.