subtitle option

[kljkjkk]

Hi. Why is there no option to add a subtitle to an attach file question? The document says there should be one, but it is non-existent on my end. 

https://support.microsoft.com/en-us/office/add-questions-that-allow-for-file-uploads-6a75a658-c02b-4...

Thanks

[#2]

or is there an option to edit/delete the subtitle I've given? Thanks