Once you get things setup right you can change the /etc/profile.d/10-emulationstation.sh file to boot directly into AM if you want.
If we are talking about the 4beta2 the best way is to edit the file /opt/retropie/configs/all/autostart.sh and change emulationstation to attract
Piggei is correct. You need to change the /opt/retropie/configs/all/autostart.sh file to change the boot. This can even be done over the samba network share \\retropie\configs\all\autostart.sh. The /etc/profile.d/10-emulationstation.sh file was used prior to the beta and if you upgraded to the beta.
This is a pretty cool new change. You can even setup the file to boot kodi and enter emulation station or attract-mode when you exit kodi.
Yes, you can alsouse the E option in the autostart setup to edit the file...
Maybe in a future we can modify the scriptmodules/supplementary/autostart.sh and add AttractMode... atm the best way is to use the E option...