It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
Mendeley picks up information from the PDFs and websites you import from. This is not an exact science, so it is ALWAYS a good idea to review and edit your references accordingly. Any references that need to be reviewed will have this icon:
In Mendeley Desktop:
To the right of the selected reference are the Details
Check to see if the information is correct
If it isn't, fill in the correct title
Click Search by Title
If this doesn't retrieve the correct information click on the appropriate fields and fill in the correct information
When everything is correct click Details are Correct
After adding references either from PDFs or the web, you can edit the references if information is missing or incorrect. This video explains how to search by DOI, by title in Google Scholar, and manually edit information.