Do you have your DS set on Auto Mode, if so the DS will automatically start up any games that are inserted.
Deselecting Auto Mode:
If it's on Auto Mode, any games are automatically started. To deselect auto mode you just need to start up your DS without any games in either of the game slots, then it'll go to the DS screen, since no games are in for now this screen is useless right?
To select Manual Mode ( where it goes to the selection screen ) as your preffered setup, you'll see a small icon of what resembles a DS at the bottom of the menu screen. Remeber your games are still not inserted at this point yet. Use the directional pad to select the mini icon, or you can tap it twice. Tapping it proves more difficult though due to it's position. Once selected a toolbar of four options will appear, tap on the one displaying a wrench. From that box three other options should appear, tap on the one shown as an arrow pointing halfway through a rectangle (start up settings) you want to select Manul Mode. Wait a few seconds for the DS settings to save then you can turn it off. Now you'll be able to see the selection screen with your games inserted.
Summary of all that:
- remove any inserted games
- turn on to see the menu screen
- select the mini DS icon at screen's bottom
- when the four pictures appear, tap on the one of a "wrench"
- when three more pictures appear tap on the one of an arrow pointing half way through the rectangle
- two options appear, select manual mode.
I really hope thats what you meant ^_^
If it wasn't, ask one of the experts.