Inspiron 11 3157 cannot access boot menu

I'm running windows 10 on a dell inpiron 3157. I want to run an OS off of a usb drive. However, when I turn on my computer and hit either F2 or F12, as soon as the dell splash appears, windows opens anyways. The Dell logo disappears for a few seconds before a blue windows screen covers my screen, and then my sign in page appears. I have fast startup disabled. Only one time in the past hour of trying have I seen the Options for F2 and F12 appear with a blue loading bar below the dell logo. However, windows still ended up booting.

Please help!

Eric