The Primary Campaign Source is coming from the online donation in Luminate Online. The LCRM integration will always try to keep your donations in sync with the online donation as part of integration functionality. To prevent the integration from changing the LCRM donation, you would need to remove the cross reference. If you only want specific donations in the campaign to be changed, then this request would need to be handled in Professional Services. They have ways of marking records as "do not sync". Speak with your account manager if you're interested in this option.