I am entering a song into band in a box. I have chords entered at a tempo of 75 in bars 1-36. The tempo is fine until bar 29 when the tempo increases to about 4 x faster. There are red lines under the numbers 29-36. When it returns to the top to repeat, it goes back to the regular tempo. What did I do?

The red lines indicate that there is a bar settings change. Click on Bar 29 and press F5 to open the Bar Settings dialog. There is most likely a tempo change entered.

One tip is that you can click the Chord Display button (view toolbar) --> Layers --> Bar Settings, and this will show you bar settings details on the chord sheet.