HP 35s Programming Question

[Ishtar]

Hi!
I love calculators and just got an HP35s (I code in assembly, so RPN just makes sense to me). But... after a few days and reading (even bought a book), I keep running into a wall. I am sure it's SUPER easy and I just am reading wrong, but I wanted to ask if any of you knew how to set me stright.

I write a simple program, call it A, and then I try to write another, but all I can seem to do is edit A. From an assembly prospective, it's like I cannot switch the code segment register.

GTO
..
[teal right arrow]
PRGM
A001 LBL A
A002 INPUT X
A003 2
A004 RCL X
A005 *
C

This works great and performs 2 * X. When I try to add a new program, call it B, I cannot get the calculator to switch to a new memory space. I am sure this is so simple, but the books I have read/bought either don't cover it or what they do show doesn't seem to work. Here's what I do next, starting from the starting input screen:
GTO
..
[teal right arrow]
PRGM <- here, I just see program A again. Typing GTO B doesn't work and says NONEXISTANT
A001 LBL B <- when I switch the label to B, the program becomes B, but A vanishes. Same code segment.
B002 INPUT X
B003 2
B004 RCL X
B005 *
C

Any ideas? This must be super simple and I just don't see it.
~Ishtar o_O