When you detect that an incorrect agent is paid you have the option to (re) assign the Rep ID to the correct agent. You can also transfer the account if the value you are using / importing for Rep ID and Account is the same.
Important Note: If you find that after transferring an account it is reverting after calculating or after moving a Rep ID is causing more items to be moved than you want it means your Import Matrix/Transfer has the Rep ID and Account Number as two separate values. If it is an Intelisys transfer/matrix please set Rep ID to Account Number and Account Number to Account Number, then delete the items and re-transfer/re-import them into your current run. The reason for this is if Rep ID is a different value from the Account Number it will group all the Account Numbers under that Rep ID and will force you to move all the Accounts at once. Intelisys uses their own Sales Agent ID as their Rep ID so if you want better control over which accounts are assigned make the Rep ID field from their transfers/matrices be Account Number.
An easy way to know which Rep ID you need to assign is to have a second window open with the items, if you view an individual item you will find the Rep ID in the Info area showing in the screenshot below.
Top menu >> Reps >> View the rep
Click Assign located in the Rep ID box
Choose Assign existing Rep ID
Select the supplier by clicking on the supplier name
Leave the radio button From assigned Rep IDs and find the Rep ID in the dropdown or paste the ID if you have copied it.
Finish when done.