kubectl config set-context --current --namespace=devops-tools
I like my answers short, to the point and with references to official documentation:
Answer:
kubectl config set-context --current --namespace=my-namespace
From:
https://kubernetes.io/docs/reference/kubectl/cheatsheet/
# permanently save the namespace for all subsequent kubectl commands in that context.
kubectl config set-context --current --namespace=ggckad-s2