Open the 
General Ledger
Setup window.
On the Dimensions tab, in
the Global Dimension 1 Code
field, click the AssistButton 
and select a dimension. Click OK
to copy the code to the field.
Repeat the procedure for Global Dimension 2 Code field.
A global dimension is a dimension that you can use as a filter anywhere in Microsoft Dynamics NAV. You can set up two dimensions as global dimensions. Choose the two dimensions that you will use most frequently in your reports. You can, however, use any dimension as a filter in the Analysis by Dimensions window.
Open the General Ledger
Setup window.
On the Dimensions tab, in
the Global Dimension 1 Code
field, click the AssistButton and select a dimension. Click OK
to copy the code to the field.
Repeat the procedure for Global Dimension 2 Code field.
Changing a global dimension requires that the program makes changes to all the entries posted using that dimension. This can take some time. To avoid having to make such a change, you should choose your global dimensions carefully.
Setting Up Shortcut Dimensions