You may be able to configure certain aspects of RealVNC Server or RealVNC Viewer from an Options, Preferences or Properties dialog, or from an in-app Settings menu on your tablet or phone. Note that for RealVNC Server, you must typically be an administrator:
Sometimes, you might need to configure both RealVNC Viewer and RealVNC Server, for example when tweaking performance.
Advanced users can use the parameter system to fine-tune almost any aspect of RealVNC Connect. This is available either from the Expert tab of the Options dialog, or at the command line.