Language-specific search and indexing
Text indexing uses the base language, which is set on the Account Settings page and applies to all users of the customer tenant. Users can enable other languages, but those will not be indexed. Full-text search of languages other than the base language is not guaranteed.
If you choose to change the base language from the Account Settings page, please ask support to re-create full-text index for your company.
The minimum length of a query for text search is one character for Asian (multibyte) languages and three characters otherwise.