Hi,

I believe that typically the versions installed with a distribution are updated by Ubuntu and their maintainers, and often this includes security fixes only rather than large upgrades.

Since, for whatever reason, it’s not up-to-date you could opt to switch to packages maintained by other people. One popular one which gets fairly regular updates is ondrej/php which you can find and read about here: https://launchpad.net/~ondrej/+archive/ubuntu/php .

I’ve had a quick look for a guide and the one I’ve found is a few years old but the process should be pretty similar if you’re able to work through any issues that arise.

https://www.digitalocean.com/community/tutorials/how-to-upgrade-to-php-7-on-ubuntu-14-04

I couldn’t say if or when DO themselves might update their distribution but hopefully those two links might help you in the right direction.