There are cases (particularly in re-installation of an agent) where you may need to assign your new installation of your agent the id of the old agent so that it continues to be referenced by all the tasks you already had paired to the old agent. 

1.Find the agent id of your current agent you wish the new installation to use (the number):

On your sever where you have 2.your new agent installation locate the qname file for your installation, the default location is '/var/opt/universal/uag/var/qname' however yours will most likely be at one of these three depending on which environment your agent connects to:
          /var/opt/universal-dev/uag/var/qname
         /var/opt/universal-qual/uag/var/qname
         /var/opt/universal-prod/uag/var/qname

3.Change the number in the file to match the agent ID you want the new installation to be tied to and save it. Restart the agent process. 

4.In about 3-5 minutes you should see the agent is your new agent based on the started date. If you are all unsure it worked contact the stonebranch provider team.