Updating definitions of hosted feature services

[ChristianSailer3]

How  can I update definitions of hosted feature service?

When I try to access at http://services1.arcgis.com/XYZ/ArcGIS/admin/services as Administrator, I receive the response:

Current Version: 10.51

Services:  There are no layers available.
Supported Operations:   No operations supported on this service. 

Although I have around 100 running hosted Feature Services...

[RobertScheitlin__GISP]

Christian,

  What specifically do you mean by "update definitions". Hosted FeatureServices are not like ArcGIS Server service that you won on your own local machine (i.e. browsing the REST service directory is not allowed) instead you control these services in your orgs content page on AGOL. From your Feature Service Page on AGOL you can Update Data, Make schema changes to attributes on the Data tab and  control editing on the settings tab.