A bit late to the party, but better late then never I guess?
As mentioned in this thread[1], you can change the number of rows in the subscription tab. However, this will only affect your own view of the dashboard, and not other users.
I’ve created an issue at issue.bestpractical.com for this, so lets hope it gets fixed!
[1] Number of displayed rows of a saved search in dashboard - #2 by Markus.Wildbolz