Why did France's overseas trade suffer during the French Revolution?

First of all, you should probably look in your own text
for this because different texts can emphasize different things and what I think is most
important may not be what your text's author thinks.

To me,
the most important factor that harmed France's overseas trade during the Revolution was
the fact that the Revolution really hurt France's domestic industries.  In order to sell
stuff to people overseas, you have to make it first.  France's "manufacturing" sector
was really tied in to the old order and so it was seriously disrupted when the
Revolution started to destroy that old order.  Since it was disrupted, there was less in
the way of goods for France to sell overseas.