RSS Feeds will not display more than 10 items

There are a mountain of posts regarding this issue and – despite hours of fiddling, into the wee hours of this morning – I could not get this resolved. I have a WordPress installation which is an Amazon affiliate store – actually, I’m just helping a friend who bought the thing, and, it had quit working with Amazon(it was not a WordPress site). If you Google this issue there are miles of posts, and most people seem to get it resolved – I had no such luck.

I am trying to display RSS feeds – in this case, from Amazon – on a WordPress site. I tried a variety of plugins, and most worked. But virtually every one of them would only display a maximum of ten feeds. I settled on a plugin called “rss-in-page” because it displayed the images, just like Amazon (most do not).

I found a reference to this plugin, and the problem, on www.remarpro.com. It suggested a hack to the plugin’s php file, which I performed. Still, it will only display 10 items. Of course, I went to Settings > Reading and adjusted “Syndication feeds show the most recent” to a variety of values higher than 10 – all of which did nothing. I disabled every other plugin. Again, I tried a variety of plugins and they all did the same thing. Part of the code for “rss-in-page” is a parameter to choose the number of items to display. Of course – again – I adjusted that value. It simply refuses to display more than 10 items.

The page is temporarily parked at:
https://www.guymerritt.net/?page_id=267

Can anyone throw me a bone, here…? What on earth is missing that I cannot set this thing to a value higher than 10….? Thanks.