How to control if Invoice Creation appears in the Chatter Feed
In Classic
- Go to 'Setup'
 - Click 'Customize'
 - Select 'Chatter'
 - Go to 'Feed Tracking' (or search setup for 'Feed Tracking')
 - Find the Invoice object in the list of Objects
 
In Lightning
There are a couple of settings that can cause Invoice activity to affect Chatter
Option One
- Go to 'Setup'
 - Click 'Feature Settings'
 - Select 'Chatter'
 - Go to 'Feed Tracking' (or search setup for 'Feed Tracking')
 - Find the Invoice object in the list of Objects
 - From here, you can enable or disable Chatter Feed Tracking for the Invoice
 

Option Two (if Option One doesn't work)
- Go to 'Setup'
 - Click 'Customize
 - Select 'Chatter'
 - Go to 'Feed Tracking' (same screen as above)
 - Select 'User'
 - Uncheck 'All Related Objects'
 
Please be aware this may have company-wide implications, and other related objects might stop posting updates to Chatter
 
