This seems to be a glitch. Words containing apostrophes cannot be found using the search function.
For instance. If a document contains the phrase “It’s Dave’s birthday”, and I do a search for the words “It’s” or “Dave’s”, I get no search results.
Searching just for “Dave”, however, does find the first 4 letters of “Dave’s” - so it seems that the search function does not recognise apostrophes.
This has been reported before.
I don’t know if a fix is planned (I have no connection to L&L), but the problem is caused by the fact that the apostrophe may be a straight “typewriter” quote or a smart (curly) one; typically, if you type into a dialogue box you will type a straight quote (the plain keyboard character), but when you type into Scrivener, it will be converted into a curly (typographer’s) quote. That’s why the search fails.
You can get round it by using Regex (some basic tips here https://medium.com/factory-mind/regex-tutorial-a-simple-cheatsheet-by-examples-649dc1c3f285, if you’ve never used it), which is helpful if you have a mix of straight and curly quotes in your text.
However, if they’re all curly, you can use Windows Character Map to just insert the correct character (U+02BC Modifier Letter Apostrophe) in the search box.