I might be a complete brainlet so excuse my take, but when animals think and do things, the weights in the brain are constantly being adjusted, old connections

I might be a complete brainlet so excuse my take, but when animals think and do things, the weights in the brain are constantly being adjusted, old connections pruned out and new ones made right? But once LLM is trained, that's kind of it? Nothing there changes when we discuss with it. As far as I understand from what I read, even our memories are just somehow in the connections between the neurons