Hi @Ben4, regarding the FX settings for Neural Mix parts resetting when you reload djay, this is normal behaviour. There is no setting for this. You will have to adjust it as desired each time you launch djay. The default is for FX to be applied to the entire Deck.
Regrading the Crossfader assignment, this setting should remain where you set it when relaunching djay. Please provide more details so we can help troubleshoot your issue.
What OS and OS version are you using?
Please provide specific details about the laptop, tablet or phone you are running djay on.
What version of djay Pro are you using?
Are you using a DJ controller? If so please provide details and confirm you are running the latest firmware.
Does your DJ controller also have a Crossfader curve control? If so, what is it set to?
Is this a new issue since a recent OS or djay update?
Thanks!