There are several ways to set negative keywords:
You can set one-word negative keywords in the Keyword parameter in the keyword itself.
Moving negative keywords to the group or campaign level makes configuration easier and reduces the risk of exceeding the limit on keyword length (4096 characters).
If a negative keyword that is set on the group or campaign level is completely included in a keyword, the negative keyword isn't applied to this keyword.
For more information about negative keywords, see Negative keywords in the Help for Yandex.Direct.