Atmega 328p-au still uses internal oscillator instead of external

Hello all. First I used Atmega328p-PU with external oscillator 16MHz. Everything worked perfectly unless I created a new PCB with Atmega328p-AU smd. My new PCB with m328p-au also uses external oscillator 16MHz, but when I burned bootloader with the same Arduino project I used for Atmega328p-PU my PCB with m328p-au engaged internal oscillator 8MHz instead of external such as I could remove the exteranl oscillator. The problem is that atmega328p-au slowed down in two times. Can it be corrupted microcontroller or I did something wrong?

Sounds like you did not get the fuses burned.

How can I burn fuses?

Install the bootloader using the IDE.
Tools: Select board (such as 5V 16 MHz Promini, or Uno
(be sure to select that same board type later)
Tools: Select Programmer
Tools: Burn Bootloader

What do you have for a programmer?

I have USBTiny ISP, and I use my microcontroller like Uno Board.

Thank you. I did everything as you said and it works!