I just installed GLB.
I load a demo, hit F5 and OK. Fine.
Load another demo. Press F5, and it runs the previous demo.
No matter with demo I load, F5 or F8 just run the very first app I loaded.
It should be stupid, but I got no clue how to.
How did you load the second demo? You should use "File > Project > Open"
I think you loaded a single .gbas file instead the project (.gbap).