Instrument change seems only to change the measures from beginning to instrument change

Sorry - if I could, I would delete it on my own. Seems as if I misunderstood the working of this feature.

If I have e.g. a simple melody (one treble system), then apply in a measure the Intrument change by adding "Instrument text". I select the measure and work on note line options, changing the instrument to "trumpet in Bb". Now the first measures will be changed to trumpet, transposed correctly, but without any key change.

Shouldn't the change work on the measures after the change?

GIT commit: d08e14c