What is the default voting system after submitting a democratic proposal?
tl;dr: the default for public proposal is positive turnout bias.
If you submit a public proposal to democracy module (as you show in the screenshot above), once it is up for vote, it will be tallied with a positive turnout bias (super majority approve): this means that, in order to be approved a heavy super-majority of
aye votes is required to carry at low turnouts, but as turnout increases towards 100%, it becomes a simple majority-carries.
For your proposal to pass you need to lobby for a big turnout: the turnout increase lowers the required
Aye votes for the proposal to pass.