If you wish to change the scan listener port post installation, then follow below steps.
Here we will change the port from 1522 to 1523.
1. Check the scan listener configuration

$ srvctl config scan_listener
SCAN Listener LISTENER_SCAN1 exists. Port: TCP:1522
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:
SCAN Listener LISTENER_SCAN2 exists. Port: TCP:1522
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:
SCAN Listener LISTENER_SCAN3 exists. Port: TCP:1522
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:

2. Modify the port using srvctl

srvctl modify scan_listener -p 1523

3. Restart the scan_listener

$GRID_HOME/bin/srvctl stop scan_listener
$GRID_HOME/bin/srvctl start scan_listener

4. Check the configuration again:

$ srvctl config scan_listener
SCAN Listener LISTENER_SCAN1 exists. Port: TCP:1523
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:
SCAN Listener LISTENER_SCAN2 exists. Port: TCP:1523
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:
SCAN Listener LISTENER_SCAN3 exists. Port: TCP:1523
Registration invited nodes:
Registration invited subnets:
SCAN Listener is enabled.
SCAN Listener is individually enabled on nodes:
SCAN Listener is individually disabled on nodes:

5. Change the remote_listener parameter in database:

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
remote_listener                      string       localdb-scan.dba.com.sa:1522

Alter system set remote_listener='localdb-scan.dba.com.sa:1523' scope=both sid='*';