Close all drawing files and then exit DataCAD. Open "Computer" and then go to the C:\DataCAD 17\Support Files\ folder. Double-click on "dcadwindialogs.gui" to open the file using Notepad. locate and delete the following section (your values will be different):
[LyrMgr] Maximized=0 Left=1610 Top=204 Width=664 Height=530 Buttons Left=1 Text Buttons=1
Save changes, exit the file, and then restart DataCAD. The Layer Manager will now open in the default position, at the center of your primary monitor.