On Land

In AC9, the keyboard shortcuts are part of the Work Environment. They are stored at 3 Resources : Work Environment : RND Profile.

Keyboard shortcuts are customized at Options | Customize | Keyboard Shortcuts, Tools tab. The settings are saved in a preferences file called ArchiCAD 8.1 Lasting.Prefs. The local version of this file is located at home : Library : Preferences : Graphisoft : ArchiCAD 8.1.0 vn, where n is the current version.

Launch ArchiCAD, and all should be well.

You have clicked some points for your dimension string. You have not checked the geometry method for the correct orientation, horizontal or vertical. Well over half the time, due to Murphy's Law, the wrong one is selected. You click to place the string, and get nothing. You have to start over. You are sad.

If you are dimensioning walls, you should be clicking on the line of the wall, rather than the corner, in order to dimension the core. (This isn't the tip; it is current standard practice. I hope someone is praying for you if you aren't dimensioning this way.) Choose the third, arbitrary angle, geometry method. With this setting, the string is forced to orient perpendicular to the wall, regardless of the wall's direction.

For two strings with the same orientation, select one, then Cmd+click on the other. The second string will disappear, and its points will be added to the selected string.