You can switch from Service Account authentication by first doing all of the delegations described in Kerberos Delegation , all without disturbing the Conquest web site.
Changing from Service Account to User Pass-through
Step 1. Start IIS
Step 2. Stop the Conquest 3 web site
Step 3. From 'Basic Settings' click the ‘Connect as…’ button
Step 4. Change the authentication method to 'Application user (pass-through authentication)
Step 5. Restart Conquest 3
Step 6. If there are failures or errors from Conquest 3 client sessions, go back over the work you did on delegations. Failing that, contact Conquest Support
Changing from User Pass-through to Service Account
Step 1. Start IIS
Step 2. Stop the Conquest 3 web site
Step 3. From 'Basic Settings' click the ‘Connect as…’ button
Step 4. Change the authentication method to ‘Specific user’ and click the ‘Set’ button
Step 5. Enter the predefined credentials of your Conquest Service Account
Step 6. Restart Conquest 3
Step 7. If there are failures or errors from Conquest 3 client sessions, check and correct the permissions for the Service Account. Failing that, contact Conquest Support