You can find information about changes/actions performed on the portal in 'Audit trail' section of Settings module. There will be stated that Opportunity has been updated, the date and the person who has edited the Opportunity.
Please follow this link to find more information about 'Audit trail' feature.
Hi Alex, thank you for your quick answer. Anyway, as I undesrtood the Audit trail keep a track of who updated the opportunity BUT not which information, in my case was not possibile to get if the update was related to the opportunity stage. Right? Let me know. Thanks Beppe
Unfortunately, there is no opportunity to find out what information was changed in Opportunity in the current version of ONLYOFFICE. We are planning to add a feature of reports in CRM module, but we can not tell exactly when this feature will be released.