Changing default time to long time ago

Tania
i tried

"from": "January 1st 1939", "to": "January 1st 1949", "mode": "quick"
and "from": "1939-1-1", "to": "1949-1-1", "mode": "quick"

none of them are working i saved the param restart kibana and it sent me back to -15 minutes even if the param shows me the dates i choose.