If you are setup with a Direct Integration Software (QuickBooks Online, QuickBooks Desktop, Xero, or Intacct), you can re-sync your Accounting from the Locations tab in Settings. 

After selecting the location, the Sync Accounting button will be in the top-right corner. 

If using a CSV Based Export, you can reach out to your Customer Success team for help at cs@ottimate.com. They will be able to provide better details on changing your Chart of Accounts. 

If it's changes to single GL accounts, feel free to check on How To Add / Edit A GL Code? for better details.