Updating Themes. Parent- Upfront, Child -Spirit

Hello, I apologize if this has been asked before. I can’t seem to find a straight answer. It seems to me that I should only be updating my child theme – Spirit. However, in my dashboard it told me that my Upfront needed updating. When I did that it messed up my site so then I reloaded Spirit and it was fine. Do I ignore all updates to Upfront and only update Spirit? I have found that I can only use Upfront to work on my site and if I go thru my dashboard into the Pages – they are not saved.

Do you have any documentation that explains this? Or clears up the confusion between when or what to update? (I love the Spirit theme btw)

Thanks so much,