Trouble installing Aggregate

@yanokwa,
Am relatively new to ODK and have been struggling with a number of issues. One of them is how to update my version of ODK Aggregate. Currently, am using version 1.6.1. I have read various update notes on how to upgrade including not updating to the latest version, but rather going through all the upper versions. I have also used briefcase to back up my data and also disabled submissions. However, at the point of uploading the token to aggregate, I get an error. I am sure that I have not changed the ODK Aggregate Instance, my username, and the application ID. Kindly advise