Hi gchq,
Yes! If you select the text field and then go to the "Paragraph" window (Shift+F5).
At the top of this window there is a line "Currently editing Caption and Value" and an arrow to the right. First consider if you want the caption (legend) or the value or BOTH to be aligned to the top of the text field. Use the arrow to change this option: "Edit Caption"; "Edit Value"; or "Edit Caption and Value".
Beneath this are a series of buttons for alignment and justification. All you need to do is hit "Align Top" and this will be applied to you choice above (Caption, Value or Both).
Good luck,
Niall