There are multiple places to control text size for labels.
1. Filter for "label" or "text" in Management Tools.
2. In the Drawing Styles Manager>Labeling Strategies>Beams>(Choose a token and adjust text size for the label)
3. While doing manual labeling, start "Insert Label" command, type in "C" to edit content definition, expand the proper entity ie beam, plate, etc., adjust text size.