Knowing exactly where your knowledge ends is a kind of smart nobody hands out trophies for.

Most errors come from confidence that continues past the edge of what you actually know. Being able to locate that edge takes more understanding than talking fluently up to it, and it gets rewarded far less, because it sounds like uncertainty. People trust whoever never hedges, right up to the moment that trust becomes expensive. Knowing your limit is a form of accuracy.

Practise saying that you are not sure and that you will find out. Then actually find out and come back with the answer. That pairing builds more credibility than confidence on its own.