Question about user vars

[Dirk.nl]

I'm new on this forum. My name is Dirk Hartland living in a village south of Rotterdam in the Netherlands. Retired, 41 years worked for a electrical company (van Rietschoten & Houwens) as consultant for offshore control systems for crane and pipe-lay barges (Hereema, Allseas, etc.)


Questions about HP Prime's user variables.
I'm new, sorry, maybe already asked.
Software version 6975

First item:
I have made two very simple test programs (TEST1 and TEST2) to test the behavior of the exported user var's. TEST1 export var = AA1 with the value of 12 and TEST2, the same var AA1 with the value of 24.
First I programmed TEST1 and second TEST2.
First running TEST1 and second TEST2.

Results.
vars-user-TEST1-AA1 = 24 (I expected a value of 12)
vars-user-TEST2-AA2 = 24
command line; AA1 = 24
command line; TEST1.AA1 = 12 (correct!)
command line; TEST2.AA2 = 24

I have tried running first TEST2 en secondly TEST1, no difference.

Question:
How must I interpret the results of the user vars and what is the difference between selecting AA1 from function "vars-user-TEST1-AA1" and from command line, "TEST1.AA1"?
In both cases I select TEST1.

Second item:
In a solve app I used a variable Ul (U line)
I changed both TEST programs. Both programs, export vars are Ul.

First running the app, Ul = 440.
vars-user-user variables-Ul = 440
vars-user-TEST1-Ul = 440
vars-user-TEST2-Ul = 440

Running TEST1 and TEST2
solver app Ul = 24
vars-user-user variables-Ul = 24
vars-user-TEST1-Ul = 24
vars-user-TEST2-Ul = 24
command line, TEST1.AA1 = 12 (correct!)
command line, TEST2.AA2 = 24

Deleting TEST1 and TEST2
solver app Ul = 440 (automatically back to 440!)
vars-user-user variables-Ul = 440

Question:
User var behavior is about the same as the first item.
Ul in solver app automatically goes back to 440. Was the value of solver app's Ul saved elsewhere?
How are user vars presented and organized inside function VARS? (Inside Prime's memory?)

Sorry for my bad English.
Greetings, Dirk.nl