To activate image uploading in this theme(Both for Featured Images and Logo & Favicon upload in theme options) follow this instruction:
Creating Upload Directory
If you haven't set up your default upload directory then
1. Using FTP or hosting panel create a directory in your Q2A installation to upload files.
2. open your "qa-config.php" file and define "QA_BLOBS_DIRECTORY" constant to point to your upload directory using this code
define('QA_BLOBS_DIRECTORY', QA_BASE_DIR . 'files/');
you can change 'files' or QA_BASE_DIR . 'files/' to point out to right path.
3. visit Theme Options, and in General tab you should set "Path to Featured Image" which is absolute URL which shows where your images are uploaded(in this demo for example: here)
right above that field you can activate featured images, so your users will be able to upload images for each question too.