This could again be a parameter in a config file?
See this topic.
The idea would be to have a configuration file on the drive, kind of simple txt file containing a list of key=value lines, these setting some global or other parameters.
In this case, something like
# Envelope 1
Envelope1MaxAttackTime=15 # maximum length of attach time, in seconds
Envelope1AttackCurve=log # log/lin/exp
Envelope1MaxReleaseTime=15 # maximum length of release time, in seconds
Envelope1ReleaseCurve=log # log/lin/exp
FixedEnvelopeRelease=1.2 # maximum length of release time, in seconds
And so on 