While you were running a report (View password request) for the whole month, you were only able to get report for last 3 days. The question is what is the way where you would be able to get report for whole month.
By default the Credential Manager settings limit the report to 5000 rows, see 'Credential Manager Operation Settings
this is the reason you cannot see more than this number of rows, is not linked to days but entries.
Maximum Number of Report Entries
Sets the number of Credential Manager entries in a report. The default is 5000. We recommend that you limit entries to less than 5000 records. The maximum size ultimately depends on the type of report, its output format, and the available memory in Credential Manager. If an HTML report runs out of memory, try generating a CSV or a PDF file instead. Alternatively, use the setReportRowLimit CLI command.
Increase the number of rows per report, be aware of the capacity of the server as indicated in the Official Guide described above
To change this go to settings - Credential Manager - Maximum number of Report Entries