Easy way to change multiple units

[iggleton]

I have 10 buildings with 50 identical units. I just made some changes to one of the units, mostly just moving door locations and window sizes. I don't want to manually repeat these changes for all 50 units. How can I automatically change the other units?

[Complex Potential]

If the units are adjacent and in neat lines you could just copy and paste the one you have across. It's quite fast because each time you copy you can do twice the number of units as on the previous copy.