iPhone 6+ problems v11

My phone was doing a few quirky things all along. Nothing significant. But v11 installed and I am ready to take a hammer to this over priced @)&)&;!

V11 has good features but Siri seems to be lost, can’t respond to my voice most of the time.

Phone acts like it’s possessed at times.

I’ll start a video and a minute in, it will jump to an earlier video or replay the one I am watching.

Everything is slow or non responsive

I have virus software.

Figured I would logout of my phone and create a new id, just in case my id is being tracked and being used to slow my system. But apparently I can’t accomplish that, I keep getting errors.

I just bought this phone 1.5 years ago.

The last thing I want to do is spend another $800.

Need some help please!

Jeff