If you choose the schedule for Weekly and check off the days to run, selecting the Save option will uncheck other days to run the Queue. Only the first day (the day the queue is scheduled to run) will remain checked.
This is resolved in 7.96 patch 13, released in September - October 2018 and applied to databases in Blackbaud Hosting Services. If your database is installed locally, download and install the latest version and patch, if applicable.
In previous versions, select Save and Close for all days to remain checked instead of Save.