You need to contact your host about it. Obviously, they gave you some directives to add to the bottom of your .htaccess file to upgrade your PHP to 5.4. For starters, you will need to edit your .htaccess file manually and put them there.
Then log in to administrator, go to Components, Admin Tools, .htaccess Maker and add these directives to the custom directives to add at the bottom. This is why we have that text area there, as documented. After clicking on Save and Create .htaccess your generated .htaccess will not revert your PHP version back to 5.2.
Alternatively, please ask your host to make PHP 5.4 the default PHP version for your site. This is the best approach, but not all hosts are willing to do that.
Nicholas K. Dionysopoulos
Lead Developer and Director
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