test = "now 234 here"; is wrong, you should use str_cpy(test,"...");
setdigits does not support %s since the second or third A8 version.

and due to it:
pan_setstring(PANEL*, var num, var x, var y, FONT* font, STRING* str)
you should set "num" properly if you want to modify it. 1 if the 1st, 2 if the 2nd... it is 0 on creating a new one.