There are two main ways to work:
1. Writing text here. When it is convenient to format only selected words: select the text you want to format then press the corresponding format button
2. Writing all text in another place, formatting only needed parts of the text here. When you paste the text here, press the button to apply the desired format, then copy the formatted text back to where you are writing
To remove a format, select the formatted text and click the corresponding button. You can also remove the format from the entire text by clicking the button without selecting any text