Sometimes it is useful to cover vias with solder mask. Here is how to do it in DesignSpark PCB. First the solder mask with the vias exposed:

1. Choose Design Technology… from the Settings menu

2. Click on the Solder Mask row and then the Edit… button

3. Uncheck the Vias setting and click on OK.

4. Click on OK to close the dialog window.

At this point the solder mask should automatically update to show the vias are now covered. If it doesn’t deselect the layer and reselect it to force a refresh.