Download a software called "S7Edit" on the Internet first. If it is a compressed package, decompress it and use it.
Open S7Edit software.
Then find your archive file in the game installation directory. The file name looks like SG7-00X.sav. Here, for convenience, copy it to the desktop and keep it.
Then open it with S7Edit, click File-> Open in turn, and select the archive file.
After loading and archiving, click on the military commander to find the military commander who belongs to your monarch. Take Ding Yuan as an example. When found, right-click the name of the military commander and select Modify.
Then enter the detail information interface of the military commander and find the experience column in the red box below.
Then click the left mouse button on the value column to enter the editing state. Because the rank of a military commander depends on experience, modifying the number of experiences can achieve the effect of modifying the rank. After the modification is completed, click File → Save, and after selecting the save path, copy the newly obtained archive file into the archive directory of the game installation directory, and the level of the military commander will change after entering the game again.