@tellingmachine The settings for previous prints aren't accessible in MatterControl, but the .gcode files which were created to run the prints are stored in the MatterControl data folder in .../MatterControl/data/gcode. At the bottom of each .gcode file are all the slice settings used. Just line up the time and date in the History tab with the time and date on the files to find the one you want.
Here are the locations of the data folder for various operating systems:
Windows: C:\Users\%Username%\AppData\Local\MatterControl (AppData may be hidden)
Mac OS X and Linux: ~/.local/share/ (.local may be hidden)