I'm running Windows 8.1 so this might not exactly match you if you are running Win 10. When the onscreen keyboard opens up there should be an icon on the lower right side of he keyboard with a down pointing triangle. Tap that and select the keyboard style you want for the default.
You do know that Windows learns your handwriting, right? The more you write, the better it gets. You teach it by selecting the correct words from the suggested ones.