discuss.answer
There is a discussion about this here:
https://forums.modx.com/thread/78243/bulk-search-and-replace-throughout-resources
Bob's snippet at the end of the thread could be a starting point, although I think it would need adapting to cover every field in which you may have the data you want to change.
In the future you might find ClientConfig useful as it could help make a situation like this trivial to resolve.
https://docs.modx.com/extras/revo/clientconfig
Thanks, will remember that (clientconfig)
One way to go would be to create a new System Setting (with or without ClientConfig), called company_name, with the new company name as the value. Then replace the current company name with [[++company_name]] wherever it appears. You may need to change it in chunks and templates as well if the company name appears there.
Also sounds like a good solution, in this case it was a website I've built in 2013 and one of the first ModX projects I did. I was a bit of a noob back then : )
Don't forget possible old names in pagetitle, longtitle, introtext, description, menutitle fields.