(Easy?) Newbie enquiry re: pointers

[kakuta Safe-mail net]

I am currently attempting to write my first GTK program, which is
 a graphical mp3 jukebox frontend to the mpg123 linux command.
I wish to have each button on a grid correspond to a different mp3 track. To do this I pass a pointer to a 
string (the name of the mp3 file) to the respective button callback functions.  This all works 
 well -  the problem is that I have also built a 'reload button'
which refreshes all the strings so that the same button then plays a
 different track to before the reload. 

The problem is that 
 even though the strings the pointers point to do seem to change 
 (I write them out on leaving gtk_main) the buttons still seem to point to 
the orignal strings, even though they have been overwirtten.
Thus the button seems locked on to the original mp3 filename
 even if I overwrite this string.

I guess this problem is perhaps easily overcome? (I can supply whatever details you may require including the 
code itself).

Many thanks,
              Dan.
p.s. I am new to GUI programming so please keep the advice at 'idiot level'!