What’s new in LibreOffice 5.4:

• a new standard color palette
• improved file format compatibility
• importing PDFs now yield much better quality
• support for OpenPGP key signing of documents on Linux
• better performance of LibreOffice Online
• and many new improvements, see release note.

How to Install LibreOffice 5.4 in Ubuntu:

For all current Ubuntu releases and the next Ubuntu 17.10, the LibreOffice packaging team built the packages a few hours ago into the PPA.

! Although the package version marked as “rc3”, it is assumed to become the final release. See the PPA description for details.

1. Open terminal via Ctrl+Alt+T or by searching for “terminal” from app launcher. When it opens, run command to add the PPA:

sudo add-apt-repository ppa:libreoffice/ppa

Input your password (no visual feedback while typing due to security reason) and hit Enter.

2. Then simply launch Software Updater and upgrade the office suite by installing the updates:

Uninstall:

You can purge the PPA repository which also downgrade to the stock version of LibreOffice in your Ubuntu by running command:

sudo apt-get install ppa-purge && sudo ppa-purge ppa:libreoffice/ppa

Source: How to Install LibreOffice 5.4 via Official PPA in Ubuntu – Tips on Ubuntu