The following help page "Create Maple Initialization File" will tell you all. Basially, you have to create, or update, a file called "maple.ini" (note that the file is without any version number or anything else).

From the online help, for Windows, we can read:

Under Windows, the initialization file is called maple.ini.
If \lib\maple.ini exists, it is loaded first (where is your Maple installation directory). With a network installation of Maple, the commands in this initialization file will be executed by all users on the network.
To execute a user's personal set of commands, only the first initialization file in one of the following paths will be loaded.
1) The current working directory (for example, "c:\Program_Files\Maple\bin.win\maple.ini")
2) The \Users directory (for example, "c:\Program_Files\Maple\Users\maple.ini")
3) The user's personal profile directory (multiuser only) (for example, "c:\Documents_and_Settings\userid\maple.ini")
Maple reads and executes the network initialization file before the personal initialization file.

The path to this page from the table of contents (online help) is "Getting Started" -> "Configure Maple" -> "Initialization Files".

HTH,
--
Jean-Marc