This topic solves

The master data (accounts, projects, client address etc.) are uploaded to DeepBox here. This master data is then available for selection in the DeepBox Editor in the fields "Account", "Cost centre", "Cost unit", "Project" and "Code". It is not mandatory to upload all master data (e.g. if the client does not have any cost centres). If only the flags in the column "Display" are set, only the fields in the DeepBox Editor will be visible, but no master data will be uploaded. If the "Show" flag and the "Upload master data" flag are selected, a selection list is visible when clicking, for example, in the "Account" field in the DeepBox. Currently, the master data is not automatically synchronised. 

Can the upload of the master data also be reversed?
Yes, in Q908 click on "Select none" in Configuration & Master Data and then click on the button "Upload Configuration & Master Data".

Why is it not possible to remove the Upload master data flag for addresses in "Q908 Configuration & Master Data"?
It is mandatory to upload the own client address from the programme "6311 Client Information".