When you select the text it must show "Paragraph#?" as the selected object in the top left corner of Signlab, if it shows as "Polygon#?, Bezier#? or Polyarc#?" then it is no longer editable as text as it has been converted to a graphic object.
If you have a Paragraph of text(ie multiple lines), you can edit individual lines/characters by highlighting just the parts you need to edit.
If you Ungroup a Paragraph, it will become individual lines of text, each of these lines will show as a "Paragraph".
If you Break Path on a paragraph it will become a graphic object.
If you use Text to graphics it will become a graphic object.
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