2 solutions to upgrade the agents by keeping the customized parameters
1) During the interactive upgrade, it asks you if you want to keep the Agent's current configuration. You can select to keep it.
2) (recommended) Backup the <agent_install>dir/agentparm.txt file, and after agent upgrade,
compare the backed up agentparm.txt file with the new agentparm.txt file and merge the appropriate parameters into the new agentparm.txt file.
For more detail, take a look at the following link (section Notes)https://docops.ca.com/ca-workload-automation-ae/11-4-2/en/installing/ae-installation/installing-the-agent