Autocomplete in Safari - NOT Autofill

Hi. I'm using several MAC's. Let's go with my new iMAC 27inch running Yosemite 10.10.4 (same problem on my G5 running 10.4.11). For several years I have been entering data into a billing program via Safari (although when testing same problem happens in Firefox and Explorer). Autocomplete has been working all the way. Entering a letter or two shows a drop-down menu where I can select a word beginning with the character(s) I have begun to type. The form has several boxes. Now, suddenly, two of the form boxes will not Autocomplete. But other form boxes on the same page do Autocomplete. The ones that don't Autocomplete will not retrieve a new entry as well. Nothing works in these boxes. Other form boxes on the same page which show drop-down do take a new entry and then display in the drop-down. I deleted the page in the History list. No change. The billing company claims that they can't help since this is due to a Browser problem. Three different Browsers? My URL bar does Autofill although I understand that Autocomplete and Autofill are different animals. Checked my Safari (browser) preferences and have been reading online but no luck with this particular problem. Any help would be appreciated. Larry Winer in New York.