Site24x7 provides the 'Bulk Action' option with which you
can update/modify multiple monitors simultaneously.
You can go to 'Admin' -> Under 'Inventory' click
'Monitors' -> 'Bulk Action' -> 'Modify
Location Profile' -> Select the list of monitors(or Monitor
Groups) -> select the new on-premise poller location profile ->
Save the settings. This will migrate all the selected monitors to the
new On-premise poller.
Site24x7 also has an option to open monitors in a new tab. When you
mouse-over a monitor name, You can see the option to 'Open Monitor
Dashboard in new tab' as shown in attachment.