Intune App protection policy

We are using iOS native email and have applied Intune APP polices to the device. We also applied IntuneMAMUPN to Microsoft Excel. We are a BYOD shop and would to enable our user to use their personal o365 accounts along with their work o365 accounts. Issues we are seeing.

1. When receiving a work email with an Excel document. If the user is logged into their personal o365 account they can save the document anywhere. How can we prevent that.

2. When they are logged into Excel with their work account they cannot switch to personal account as they are told they have to log out of the work account. Is there a way to switch between the 2 accounts?

Thanks