changes to selenium configuration under jenkins 'manager jenkins' is not saved

Problem:
Data entered into jenkins admin selenium section is not saved

1. As a jenkins admin, goto 'Manage Jenkins' -> Configure Systems -> Expand 'Selenium' Advance section
2. Enter Set -newSessionWaitTimeout as 300000 (5mins) for new new test to timeout after waiting for a node.
3. Click apply/Save
4. Open Configure Systems -> Expand 'Selenium', this entered data will not be available

We need to configure this -newSessionWaitTimeout as we are lots of test than the available number of nodes so we need to configure the time for new tests to wait for freed slots.
Can we get this fix please ?