Adding Estonian letters to English-language keyboard

lisaat wrote:

How do I add the Estonian vowels Õ, Ä, Ö, Ü to my English-language keyboard?

If you press and hold those keys, you should get a popup menu where you can choose the one you want.

Another way is to do option N and then O to get Õ, option U and then O to get Ö, etc.

Enter characters with accent marks on Mac - Apple Support

Or change the keyboard to Estonian

Write in another language on Mac - Apple Support