Summary

The Hide completed issues older than option in the general settings for Kanban Boards are limited to 1, 2 and 4 weeks. To see issues older than these time windows you're forced to use the Never mind, show all option which overloads the Board.

Proposed solution

Expanding the options to 2, 3 and 5 months would allow the possibility of expanding the date range of completed issues teams want to have visible on their Board. Another solution would be to have customizable date ranges for this function.

Workaround

As a workaround, you can use the Never mind, show all option and adjust your Saved Filter to exclude unwanted issues by including a resolved >= -10w in your JQL.