When we say "you only have to do something", we are implying that the task is mandatory but not overly complicated or difficult. We can use various synonyms to express the same idea, such as "you simply need to", "you just have to", or "you need only". These phrases convey a sense of ease or simplicity, reassuring the listener that the task is not burdensome. Alternatively, we can use more forceful language like "you must" or "you are required to", to emphasize the importance of completing the task. Phrases like "it's essential that you" or "it's imperative that you" also add urgency to the communication. Ultimately, the synonym we choose will depend on the context and our intention.