How do I select text which is on top of an image?

you should be able to select the image then press ctrl+click the text. Click in pretty much the same place for both clicks.

Option 2: If for some reason this doesn't work, add a text somewhere close to the image, select a range the includes the image and the added text, right click the added text and choose select>All similar elements in range selection, then ctrl+click the unwanted text and only the wanted text will remain selected.