Now, some may not change when maximum armor is used. For example the only way you can have maximum armor on a 'Mech requires that the arms, head and legs carry the maximum possible armor. Therefore, you can't change it. Fixed armor is set by you in tons or total armor points, but you still can adjust it amongst the 'Mech's locations. You can use this to have control over the total armor, with automatic distribution and manual fine-tuning.
Manual armor is set by changing each location to have the desired number of armor points.
It will not change when you add or delete equipment, and will remain that way until you want to change it. Note that when changing the total 'Mech tonnage, the armor points may have to change, however. I like using the Select 'Mechs feature, but HMPro keeps coming up with 'Mechs which I don't have miniatures for, and I like to play only with miniatures. For all the 'Mech data files, check one of the boxes for all those you have miniatures for, uncheck it for the others. A usage screen will appear.