@nguyenhtuan: I recommend checking out Pro Mode, as this allows for deeper customistion for your photos, including increasing/decreasing the exposure. To access Pro Mode, open the Camera app > Swipe over to 'More' > Pro Mode. For further details about using Pro mode, please check out this handy guide from our friends at Samsung Australia.
Thank you AndrewL for your reply. I know this pro mode, but in daytime, when I want to shoot a long exposure photo, it's often over exposure with these setting: ISO 50, F2.4 2. I search on the internet and they recommend me to buy a ND filter, but I don't know is there any why to shoot without ND filter to get a nice photo without being over exposure. Thanks.