Q:

I cannot link toolchain to different github organization

I have a github account: https://github.com/remkohdev 
and am a member of several github organizations
I have added all organizations to the Bluemix DevOps Third Party applications authorizations.
But I cannot change the default github organization to a different organization when I enable the Toolchain on Bluemix, so that I can create/edit the source code to the repo in a different than default Github organization?

Error:
The integration could not be set up. Check the settings and try again.
Reason: Unable to update the git integration. An error occurred while cloning the git repository. Error details: Unable to read the repository on: https://github.com/eventquarry/server.git. User is not authorized, or repository does not exist.

A:

When you authorized with GitHub you probably did not explicitly grant access to the eventquarry organization. 
To fix this, first you need to revoke your token by logging into Github.com, then click settings > Authorized applications > Revoke "IBM Bluemix Toolchains". Now go back to Bluemix, and when you click on the GitHub tool you will see an “Authorize” button. Upon clicking, you will be taken to GitHub, and here you need to click "Grant Access" next to eventquarry (and all orgs you would like to grant access to) before clicking "Authorize application". 
Now you should be able to fork/clone/link with the private repositories in the eventquarry organization.

