I think I found a way; move the cross in the moddle top sideways but it's very sensitive. But now I have another question. Editing text inside a text box is very frustrating. For example, I don't seem able to delete the last letter of text
Text boxes are always horizontal there. Choose the tool "Free text" and click on the page where the text should go, then type your text. To change the text later, double-click the text box. You then edit it like normal text, Backspace and Delete work as usual, also for the last letter.