Slapdash is built under the assumption that everyone works a bit differently. We don't mind which apps you use, we'll just bring them all together and make your experience with your apps more powerful. And when our default experience doesn't quite match-up to people's workflows, we are always keen to be let people customize Slapdash to fit their needs.
One area where people have a lot of preference is around the browser they use. Some people like to keep certain apps in certain browsers; others might prefer to open something in the desktop app if it's available.
Now, in the Slapdash desktop app, you can choose which browser Slapdash uses to open things by default. Go to Settings > Preferences and you'll find a new Open Preferences panel.
If you want to control how a specific app behaves, you can do that too. Just go to the app you want to customize in Apps > Connected to see the available options.