In your Avactis store Admin Panel : Go to Store Settings -> Store Configuration-> Search Engine Optimized URLs. Set following fields URL settings ->
Category links ID : System identifier for categories. Default value is cid. This ID may be changed but cannot be left blank. Product links ID : System identifier for categories. Default value is pid. This ID may be changed but cannot be left blank. URL scheme : URL scheme – Lets you select the URL scheme to be used. Several URL scheme options are provided for your online store. Only one URL scheme is used at any given time; others are inactive. Storefront: -> Action : Set Enable support for HTML URLs (mod_rewrite). Verify integrity of configuration files and settings.
Save the changes and check storefront. The URLs would now have changed.