Well, it seems some new features, like choosing background colors for a quick filters, also applies to parameters in the workbooks. But not so in dashboards. In a dashboard, a quick filter will render with the selected background just fine, but a parameter will be have its original unadorned formatting. Unless I'm missing something?
Here's what I just found:
Formatting applied to quick filters in workbook carried over when the filters were brought onto a dashboard.
Formatting applied to a parameter in workbook did not carry over to the dashboard, but within the dashboard I could apply the desired parameter formatting. Whatever, it worked in the end.
It can take some time to get used to how Tableau applies formatting at the sheet or dashboard level; glad you got it working.