RE: Switchable graphics in Dell Inspiron 5559
You may be able to go into the System Setup (BIOS) and change the display options from Dynamic to "fixed" but I'm not sure. I don't have a version of that BIOS to review to make sure.
But the easier way would be via the AMD Catalyst Control Center. You should be able to go to the Welcome Screen in AMD CCC and select Power, then Switchable Graphics. You can select the application(s) you want to set to use the AMD card as default and from then on the system will use that video card.
Here is a link to a discussion on changing the defaults in BIOS. Remember, if this is an option it will also seriously use power more quickly then the integrated graphics and you'll see a reduced amount of time you can use it on battery power between charges.
If you have any other question, to help me troubleshoot this a bit easier, please click on my Dell Todd username and send me a private message with the Dell service tag of that system. Please keep all discussions and troubleshooting here in this open thread so that others can see what is done to answer your question.