It looks like the Label Field is set to "scores" in IGB. Assuming that is the case, IGB will show the score of the reads up to a character limit centered on the read itself.
If you are interested in comparing Phred scores between reads then right-clicking on the track label and selecting Shade base by quality may work better. If you want the score for any particular read you can click to select the read and then select the Selection Info tab which should contain the scores field.
Let me know if this helps.