It's possible to increase the duration of the smoke in a config file, but it won't be the effect you're looking for.
The real problem is the wind, which has a random direction and speed, and this blows the smoke away, where it tends to drift off in discrete clouds. Any change to the duration of the smoke hanging around the infantry or artillery would require JMM to make a program change to lower the wind velocity or give us a config file setting to choose our own wind speeds.
In cases where the program chooses a low wind speed, the smoke does indeed hang around for a considerable period of time. Otherwise the wind just blows it away.
Hook
