In my experience, many end users believe that with perhaps an hour or two of training, they will be able to create their own reports. This is not just an Odoo issue; it is a common perception that many end users have when working with any ERP system. Unfortunately, creating or modifying reports is often not as easy as it appears and should be considered much more of a developer task, rather than an end user task. Be prepared to spend considerable time practicing and acquiring the skills that are required to make significant changes to the documents and reports that are provided to you in Odoo.
Furthermore, reporting has changed dramatically in the past few years. Previously, it wasn't uncommon for many companies to be totally dependent upon paper reports and Excel sheets to properly communicate information throughout...
