You know, my honest but also meta answer is that I don't know the answer to your question.

There's a lot to unpack here and I don't know you well enough to give personalized advice. But this problem kinda requires personalized advice.

> in a way that doesn’t make it seem like I can’t be trusted that I know what I’m doing.

Why do you feel this way? I can think of several possibilities:

1.) You really really want the ability to know the answer instantly. While your mind know that's not reasonable, your heart is disappointed. As a result, your body language sends the message you don't know what you're doing.

2.) Verbal interactions are tough and you're looking for the right canned phrase that will give you time to think. However, that canned phrase sounds practiced, and people mistake it for a canned i-dont-care response.

3.) You want to people to understand why you don't instantly have an answer. As a result, you provide far too much justification, which winds up sounding guilty.

Personally, I have had great success with encounters where I absolutely don't know the answer, and I barely know where to start. Charlie asks me a question. I reply "I don't know, but Bob might know!" We ask Bob, and he doesn't want to be bothered, but he does know that Fred should know the answer. We then go to Fred, and I pay attention as the other two talk. I learn about Fred, a new topic, and Charlie winds up thanking me the most. In the future, Charlie comes to me first instead of Bob or Fred, and I wind up learning more than Bob and Fred put together.

It wasn't about how I said it, it was about putting in the effort to be present. And then people remembered I'd actually put the effort in.