Did you follow the instructions I provided above? As an alternative, you can change the pics by ftp. Upload your slider pictures, to the \wp-content\themes\minamaze\images folder replacing the existing images with your own. (or your child theme, if you are using one) But this should really be able to be done by following the instructions I gave in the post above, through the backend of your site. The text can also be changed there. To refresh what I said again, go to the admin section of your site,
click on appearance->theme options-> homepage. Once on that page, see where it says, Built in Slider, you will see rectangular boxes with a + sign and text. Click on each one and remove the existing pic, once you have removed them all, click the red button that says ‘Add Slide’. Fill in the details, Keep clicking add slide until you have added all the slides you want to show. then press ‘Save Changes’ at the bottom of the page. I hope this helps.
