Oscommerce Site MAIN language changed

I need my site to load 100% of times in spanish disregarding the browser being in english or not. Although the main language of the site is already selected as SPANISH, my website comes up in english( which is the other language). English was originally the main language but ideally my site should 100% of the times load in spanish. Only if the customer selects english should he see that language. But this website has been changed to a spanish audience, hence the need. This may be because my browser is in english. I need a fix that even if the browser is in english loads the main website [login to view URL] in the spanish version. If you read my description please quote the word "reading" in your bid. I ALREADY set the default language to spanish in the admin.(this has no effect) The provider will NOT have access to the admin I can send whatever file needs to be modified and We will work together with the change so you should agree in working like this.