You need to talk about them with your supervisors.
You need to know why they’re a good choice.
You need to know why they might be interested in your work.
You need to explore their research.
You need to think about how their work is related to yours.
You need to believe they’ll be fair.
You need them to do their job.
And you need to accept that they’re just people, same as you; they’re not on a great high pedestal, they’re just humans, filling a necessary role, and doing it because they’re highly qualified to meet the needs of your viva.