I had the same problem when I was handling multiple projects. I referred this article But it was like every time I need to switch the versions if need but this gives the flexibility for cli and web separately.

Moving From php5.6 to php7.0

For Apache, we can use the command as:

sudo a2dismod php5.6 ; sudo a2enmod php7.0 ; sudo service apache2 restart

For CLI, we can use the command as:

sudo update-alternatives --set php /usr/bin/php7.0

Moving From php7.0 to php5.6

For Apache, we can use the command as:

sudo a2dismod php7.0 ; sudo a2enmod php5.6 ; sudo service apache2 restart

For CLI, we can use the command as:

sudo update-alternatives --set php /usr/bin/php5.6

Source: server – How to have two versions of PHP installed and switch easily between them? – Ask Ubuntu