Titles in Zotero — and in bibliographic output in general — don't have multiple lines. (If you get one via copy/paste, that's a fluke, it may stripped in various place, and you shouldn't depend on it.)
There is currently some work being done — as part of the Citation Style Language that Zotero uses — to expand support for subtitles. Right now, subtitles can only be separated from titles by a colon, and Zotero will parse them automatically, but in the future I believe it may be possible to specify a subtitle explicitly. That's not the same as multiple lines, though. If you give an example of what you're referring to, we might be able to say more.
Also note that line separation is not typically considered to be part of the title, but just typography. If a title is split into two lines, that is usually separating a title and subtitle. When this title is cited, they would be separated by a colon rather than a new line.
Ah, OK — so then @lpereira0629, if the whole thing is the title, you should just put it in the Title field separated by a colon, and if you generate citations the subtitle will be handled appropriately by the citation style you're using.
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I'm using Zotero a bit differently in addition to the normal citation