[SOLVED it DOESN'T] Why does changing the comport in a 2nd instance of Arduino-IDE change the Comport in instance 1 too?

Development Tools IDE 1.x
8

I must have mixed up something. I carefully re-tested it with 1.8.13 and 1.8.16

I tested it with windows IDE 1.8.13:

double-click on Desktop-Icon for IDE 1.8.13
opening a sketch1.ino
adjusting comport to 16

double-click on Desktop-Icon for IDE 1.8.13
opening a different sketch2.ino
adjusting comport to 17

comport in instance with sketch1.ino (primary adjusted to comport 16 stays on comport 16)

croschecking with windows IDE 1.8.16:

double-click on Desktop-Icon for IDE 1.8.16
opening a sketch1.ino
adjusting comport to 16

double-click on Desktop-Icon for IDE 1.8.16
opening a different sketch2.ino
adjusting comport to 17

comport in instance with sketch1.ino (primary adjusted to comport 16 stays on comport 16)

and both worked as expected.

Thank you all for replying