OBS log shows the Avermedia is set to 720x480p in OBS. The properties screen for the device in OBS is what is exposed by the driver provided by Avermedia. I would check that these drivers are the latest and perhaps uninstall/reinstall them to make sure. Log is also showing performance issue to this device (max audio buffering reached) and a failure to set a valid resolution.
The Avermedia specs seem to indicate it maxes out at 1080p30 for capture, but can pass through 1080p60. It looks to me like you're trying to capture 1080p60, and it can't, so it's keeping your framerate and dropping your resolution.
Seamlessly record and stream 1080p30 video and record Full HD signal anywhere, anytime in its standalone PC-Free mode.
www.avermedia.com
• Max Pass-Through Resolutions:1080p60
• Max Record Resolutions:1080p30
• Supported Resolutions (Video input):1080p, 1080i, 720p, 576p, 576i, 480p, 480i
20:03:58.723: [DShow Device: 'Video Capture Device 2'] settings updated:
20:03:58.723: video device: AVerMedia C835 Capture
20:03:58.723: video path: \\?\usb#vid_07ca&pid_c835#202548900040#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\{957bd672-7934-4b55-b81a-3e22b14c679a}
20:03:58.723: resolution: 720x480
20:03:58.723: flip: 0
20:03:58.723: fps: 59.94 (interval: 166833)
20:03:58.723: format: H264
20:03:58.723: using video device audio: yes
20:03:58.723: sample rate: 48000
20:03:58.723: channels: 2
20:03:58.723: audio type: Capture
20:03:59.125: warning: Multiple frames in a packet.
20:03:59.142: Max audio buffering reached!
20:03:59.142: adding 1044 milliseconds of audio buffering, total audio buffering is now 1044 milliseconds (source: Video Capture Device 2)
20:03:59.142:
20:04:05.113: Video Capture Device 2: ResolutionValid failed
20:04:05.113: Video Capture Device 2: Video configuration failed