Does reducing message history on one device affect other devices? If I have one apple account signed into multiple devices, and I change the iMessage message history from Forever to 30 Days on one device, will this have any impact on any other devices with this same apple account?


I'm just trying to make sure I don't delete older messages on any other devices when deleting older messages on the one device.
No it does not. Each holds messages it received from the servers irrespective of other devices.