Besides the indexing mistake, something else is wrong too.
The proposed method of initialising a structure can be used only in the declaration, not afterward.
So this would be fine:
static struct{
int aaa;
char bbb;
int ccc;
char ddd;
}form[2] = {8,'a',6,'b',9,'s',5,'v'};
But to modify it later, you would have to do it like this:
form[1].aaa = 9;
form[1].bbb = 's';
form[1].ccc = 5;
form[1].ddd = 'v';