Добавить каталоги для запуска определенной версии PHP
<Directory "C:\xampp\htdocs\my_old_project1">
<FilesMatch "\.php$">
SetHandler application/x-httpd-php56-cgi
</FilesMatch>
</Directory>
<Directory "C:\xampp\htdocs\my_old_project2">
<FilesMatch "\.php$">
SetHandler application/x-httpd-php56-cgi
</FilesMatch>
</Directory>
Condemned Caribou