Created kubeconfig file but only able to access default namespace - kubernetes

Question

I used below file to create service account
apiVersion: v1
kind: ServiceAccount
metadata:
name: sa-reader
namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true"
name: reader-cr
rules:
- apiGroups:
- ""
resources:
- '*'
verbs:
- get
- list
- watch
- apiGroups:
- extensions
resources:
- '*'
verbs:
- get
- list
- watch
- apiGroups:
- apps
resources:
- '*'
verbs:
- get
- list
- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: read-only-rb
subjects:
- kind: ServiceAccount
name: sa-reader
roleRef:
kind: ClusterRole
name: reader-cr
apiGroup: rbac.authorization.k8s.io
The kubeconfig I created is something similar
apiVersion: v1
kind: Config
preferences: {}
clusters:
- name: qa
cluster:
certificate-authority-data: ca
server: https:/<server>:443
users:
- name: sa-reader
user:
as-user-extra: {}
token: <token>
contexts:
- name: qa
context:
cluster: qa
user: sa-reader
namespace: default
current-context: qa
With this kubeconfig file, I am able to access resources in the default namespace but not any other namespace. How to access resources in other namespaces as well?

Answer 1

You can operate on a namespace explicitly by using the -n (--namespace) option to kubectl:
$ kubectl -n my-other-namespace get pod
Or by changing your default namespace with the kubectl config command:
$ kubectl config set-context --current --namespace my-other-namespace
With the above command, all future invocations of kubectl will assume the my-other-namespace namespace.

Answer 2

An empty namespace in metadata, defaults to namespace: default and so, your RoleBinding is only applied to the default namespace.
See ObjectMeta.
I suspect (!) you need to apply to RoleBinding to each of the namespaces in which you want the Service Account to be permitted.