The father of Nasim Aghdam says she was angry at the company because it stopped paying her for videos she posted on the platform.
Ismail Aghdam told the Bay Area News Group that he warned police his daughter might be going to YouTube because she 'hated' the company.
Details of any payments she may have been receiving have not yet been disclosed.
The shooting comes weeks after YouTube agreed to manually review all videos in its 'preferred' section so advertisers were sure they were not promoting harmful videos.
As well as manual reviews, YouTube tightened its rules on who qualifies for posting money-making ads.
Previously, channels with 10,000 total views qualified for the YouTube Partner Program which allows creators to collect some income from the adverts placed before their videos.
But YouTube's parent company Google announced that from February 20, channels would need 1,000 subscribers and to have racked up 4,000 hours of watch time over the last 12 months regardless of total views, to qualify.
This is the biggest change to advertising rules on the site since its inception - and is another attempt to prevent the platform being 'co-opted by bad actors' after persistent complaints from advertisers over the past twelve months.
The changes came just weeks after YouTuber Logan Paul's video showing the body of a suicide victim reached the site's trending page before being removed.
YouTube's new threshold means a creator making a weekly ten-minute video would need 1,000 subscribers and an average of 462 views per video to start receiving ad revenue.