Wanted to change from displaying 5 posts to 10 posts.After checking all the settings, trying different things, scowering the forums I found the answer: a) Settings in the "Installed Plugins" page must be the same as the settings in the widget settings and b) refresh browser several times and over a 5 to 20 min. period in order to have the Twitter feed respond as expected. See below, from the widget author.
"Twitter Widget Pro will use 20 requests per hour. It can use a few more if you change settings (changing from 10 to 5 will require an immediate refresh even if it hasn't been 5 minutes since the last one). It looks like There must be other people on your server (or server cluster) using the Twitter API and it looks like your IP is burning through all it's available requests in 20 minutes (maybe faster, I've seen overly-full IPs use their whole allotment in less than a minute, and IPs with sites that abuse the API can actually run out in less than a second). Once you've used all your requests, Twitter will simply refuse to reply to any more until the time limit has passed. This is going to make your Twitter Widget act very sporadically. Consider asking your host to move you to a server or cluster that has lower Twitter API usage."