An electronic method of operating a gaming system. The method includes selecting a plurality of symbols, displaying the selected symbols, and upon the displayed symbols including one or more designated symbols, retaining each displayed designated symbol for a subsequent game round at a respective symbol display position at which the designated symbol is displayed. The method also includes, in the subsequent game round, selecting, a plurality of symbols from the symbol data, upon a further designated symbol being selected for display at a symbol display position at which the retained designated symbol is displayed, modifying the retained designated symbol to indicate that a win containing the retained designated symbol will be increased, and upon the selected symbols in the subsequent game round corresponding to a winning outcome incorporating the modified retained designated symbol, making an award of an award value corresponding to the winning outcome modifier by the increase.