How can i upgrade my pass to yearly

I have bought monthly pass,
i want to upgrade to yearly, but seem no way.
now monthly pass have expired.
wt can i do to upgrade to yearly?

I believe everything you need to do that is here https://support.plex.tv/hc/en-us/articles/201580107-Plex-Pass-Subscription-Management

I have a lifetime so don’t use those pages.

Thank you for your reply,
in case, subscription page is writing as below,
“Thanks for supporting Plex, we really appreciate it.
Your subscription is handled through iTunes. You can manage your subscription from your iOS device or iTunes”
hence ,i can only paid by monthly from itunes,
how can i change?

Unfortunately you cannot upgrade from the monthly pass through iTunes. You basically need to cancel the renewal in iTunes, then wait for your current monthly to expire, then sing up through https://plex.tv/subscription.