1. Click on the Start Menu.

2. Click on Settings (the gear icon).

3. Click on Time & language.

4. Click on Region & language.

5. Click on "English (United States)". It might be "English (SomeOtherCountry)". Just click on it.

6. Click on Options.

7. Click on Add a keyboard.

8. Add the "United States - International" keyboard.

9. Click on "ENG" or "ENG US" in the lower right corner of your screen. Choose "ENG - INTL" from the menu.

Congratulations. You can now type in perfect Español with all the diacritics, all while keeping all your symbols in the same place. Here's a crash course on how to use this new superpower:

To type Spanish accents (á, é, í, ó, ú ), hit the  " ' key before the vowel you want accented. (That's the key right to the left of the Enter key)

To type the Spanish umlaut (ü), use the same key while pressing shift, and then the U. 

To type the Spanish Ñ, press Shift + ~ (a key very near the top left) and then the N. You can also get the Ñ by holding down Alt Gr and then pressing N. 

To type the Spanish ¡ sign, just press Ctrl + Alt + 1 or Alt Gr + 1

To type the Spanish ¿ sign, just press Ctrl + Alt  + ? or Alt Gr + ?

If you need to type an apostrophe while in this mode, just hit the spacebar after typing '

If you need quotation marks while in this mode, just hit the spacebar after typing "

You can actually stay in this input mode all the time and enjoy typing both English and Spanish without switching, and without losing track of your symbols.

(This is actually a modified repost. I originally published this guide for Mac.)

If this works a bit different on your PC, please let me know in the comments.