Windows 10's printer settings allow you to customise which printer is used as the default. This is the printer which receives your document when you press a "Print" button without having explicitly chosen a printer to use.
Since the Windows 10 November 2015 update, Windows has assumed automatic control of the default printer. It will always select the device which you used last. This mode is even location-aware, so if you use your laptop in multiple buildings you'll find the default printer matches the device in your current location. However, you may want to configure your default manually if you only use other devices occasionally.
Open the Settings app (press Win+I) and click on the "Devices" category. Now switch to the "Printers & scanners" page.
First, look for the "Allow Windows to manage my default printer" checkbox. Clear it if it is ticked to disable the automatic functionality described above.
Next, find the printer you want to use as your default in the "Printers & scanners" list. Click its name and press the "Manage" button. On the next screen, click the "Set as default" button.
You'll now find your selected printer is always the default when printing new documents. Depending on the app you're printing from, you'll still be able to choose another printer for each job, but doing so won't impact any future jobs.