Can someone help me figure out why I can't choose a pixel from my business manager in this ad account?

I am trying to set up a pixel for a client that I manage. For some reason, it is defaulting to a random pixel that has nothing to do with them, and I cannot change it. It will not let me choose a pixel for website events, only giving me the option to "set up". When I try to set it up, it gives me an error and says I do not have high enough permissions? I hope someone can help. Thanks!