this is not a power store 3 issue.
It is an issue with 1 and 1.
power store 3 does not have a file called .htacess. you need to create it.
follow these steps:
1) Open a text editor
2) Start a new file.
3) paste the following code:
AddType x-mapp-php5 .php
4) Go to File -> Save As.
5) Name the file ".htaccess"
6) Upload the file to your server.
the documentation for accomplishing this is on the 1and1 site: