How to use Google Docs – Computer – Google Docs Editors Help

On your computer, open a document in Google Docs. To select a word, double-click it or use your cursor to select the text you want to change. Start editing. To undo or redo an action, at the top, click Undo or Redo . Note: To edit a document on a touchscreen device, like a Pixel Book, double-tap the document to start typing.

https://support.google.com/docs/answer/7068618?hl=en&co=GENIE.Platform%3DDesktop