If you change the font setting for the window to a variable-width font the register name field might not be completely visible.
Open the Options dialog from the Tools menu > Options. In the tree on the left, expand "Programmer/Debugger" and then select "Fonts and Color". Under "Show settings for" dropdown list, choose "Registers Window", then under "Font", choose a fixed width font.
The recommended font is the default; "Courier New".