Failed interviews in sequence for all FANG and other companies
I recently gave interviews at many companies for the senior software engineer roles. Few did not get past the phone or online test like dropbox, amazon, splunk. Others where I got through first round happen to fail in onsite in 6 other big companies. When I retrospect myself I see the way I'm explaining on a language construct or system design is not well received. Also with coding rounds giving an approach straight out of my head is also not acceptable. How can I improve myself? I feel something is going wrong. Not exactly sure how to work on them. Kindly advise.
Additional details- have 7yoe in software development