Am i missing something, or is it not possible to fill in default values in the launch pad on jobs?

Yes you can Just do:

@job(
    config={
        'ops': {
            'your_op_name': {
                'config': {
                    'some_key': 10
                }
            }
        }
    }
)

I was more thinking to easily insert the values i have as default in the graphs etc. I can see them in the right side of the screen, but not easily auto fill them in.

This feels like a reasonable request- I added an issue for it https://github.com/dagster-io/dagster/issues/11828

thanks!