recently I bought YotaPhone 2 from Aliexpress, and I wanted to update its android which is currently version 4.4.3, and when I go to Settings and About Phone, the first thing from the top is Status, and there is no System Updates option, my phone's processor is Qualcomm MSM8974PRO-AA. please help me.
The system updates differ from country to country or varies place to place. Same phone from one place may be provided with an update whereas same phone from another place cannot be updated. The reason for you not getting might just be this.
But please recheck :
According to GSM ARENA you phone can be updated to 5.0.
Also update is the must the flashing a custom rom is also an option.