Find requests in FileMaker do not detect text styles so you cannot search for text that is or is not underlined. You might be able to search for this in a calculation field that exposes the formatting tags such as GetAsSVG or GetAsCSS. Your search criteria would then need to specify the formatting tag as well as the text.
for your second question, this is also not something easily done with a find request. You might search in a calculation field that omits the characters you want to ignore. There are a number of options here and the best option depends on how many characters you want to ignore in your search Here's one example that might be used:
Filter ( OriginalFieldHere ; "abcdefghijklmnopqrstuvwxyz" & Upper ("abcdefghijklmnopqrstuvwxyz") )
This fields omits all characters except the letters "a...z" and "A...Z" and thus would ignore the # if you searched in this field instead of the original field.
thanks for your answers. but my question is: I added underline in some words, for example, happy. And then, when I "Find" the word "happy", all "happy" can be found including the one with underline. But to be surprised, the one with underline has been automatically cancelled (or disappearing) for its underline. I do not wish the underline automatically disappearing. what should I set up it or to do?
Performing a find does not change nor does it reformat data. Something else is changing the underline formatting. This is not happening because you are performing a find.