BIOS secure boot problem(acer Aspire E1-421)
I have a laptop model: acer Aspire E1-421. Recently i needed to setup a new windows on my laptop so i made a usb bootable pendrive to install new windows. after restart my laptop i press the F12 button and select the usb pendrive to boot from boot manager but after a second it start boot my old installed operating system (Windows 7). then i go to BIOS and set boot priority to usb but still not useful. then after search problem in acer community i found i have to set supervisor password and then from boot option i have to disable secure boot option but after i set the supervisor password and got to the boot option there is no secure boot option and also in my BIOS there is no UEFI or Legacy change option. i also update my BIOS but nothing changes. Is there any way other way to disable or change any setting to install the new operating system, Please help me. i seriously need to install the operating system. Thank you