Microsoft is now testing Windows 10 version 1803 build 17018 for PCs. The new Redstone 4 Update build 17018 (10.0.17018.1000 rs_prerelease.171011-1422) was compiled on Oct 11, 2017.
Windows 10 Redstone 4 build 17017 is now available for Fast and Skip ahead insiders. The latest build brings new Cortana features including Cortana Collections and more. Also, there are bug fixes and improvement to the OS.
Microsoft also released a new cumulative update KB4043961 (OS build 16299.19) for Windows 10 Fall Creators Update RTM build. The update comes with bug fixes and minor improvements. The company will release this FCU feature update to everyone on October 17th. You can download the update KB4043961 from here.