In detail:

i want row "A" to be frozen until i scroll down to "B",then i want "A" to disapear and "B" to be frozen on the highest row until i get to row "C", then i want "B" to disapear and "C" to be frozen on the highest row until i get to row "D", etc...
Ex.
A
1
2
3
4
5
B
1
2
3
4
5
C
1
2
3
4
5
D
1
2
3
4
5