How Do I Upgrade To The Latest Version If I Have Custom Templates?

I'd like to upgrade to the latest version, but when I do I get a message telling me I will lose all my custom edits. I have no idea which templates have edits or what the edits are. Does this mean I cannot upgrade to the latest version without keeping these edits?

I'd like to upgrade to the latest version, but when I do I get a message telling me I will lose all my custom edits. I have no idea which templates have edits or what the edits are. Does this mean I cannot upgrade to the latest version without keeping these edits?

How the changes were made? If you used module, all changes should be saved. If you changed default templates, these changes will be lost.