Say you use a MacBook Pro (MBP) and you have a specific monitor setup of at least two external monitors. As the main desktop you use the internal monitor of the MacBook Pro. This monitor setup you use at different locations and different monitor models.
If you disconnect your MBP from the external monitors and reconnect them, the window positions are restored. After changing the workplace and the monitor models, the window positions are not properly restored - sometimes they are mixed up, sometimes they are reversed.
Obviously Yosemite is not able to restore monitor positions correctly when monitor models have changed. But it stores the display arrangement correctly, so the monitors are known by Yosemite and identified.
How to change and save the indices of the known displays permanently?
A preferred solution would be one, where no third-party software has to be purchased.