When expressing confidence in something, there are a variety of phrases and synonyms for the phrase "was sure about." Some of these alternatives include using phrases such as "was positive," "had no doubt," "was certain," or "was convinced." Other options include saying "was confident," "had a strong feeling," "was absolutely sure," or "was entirely convinced." These phrases can help to convey a sense of sureness and certainty about a particular situation or decision, and can be used in a variety of contexts, from personal relationships to business matters. By employing these types of synonyms, individuals can effectively communicate their level of conviction and make their intentions clear.