8-Bit Binary to BCD Decoding for Three 7-Segment Displays
Almost certainly you are suffering from ground and/or decoupling issues.

Assuming you are using a solderless breadboard setup, you should do 2 things. First, find some way to beef up your ground system. Try, for instance, running ground wires vertically as well as horizontally, and use ground wires as short as possible. No big loops of wire. Second, at each IC install a 0.1 uF ceramic cap from Vcc to ground, and put each cap as close to the appropriate pins as possible. Connect each directly to the space nearest the pin. Under no circumstances should you run jumper wires from the IC to a cap placed elsewhere on the board.

This may or may not work. An even bigger issue is that you are misusing your counters. These are synchronous, not ripple. So connect all the clocks together. In each counter chain, connect RCO to CTEN of the next counter.

Finally, you need a debounce circuit on your switch. You can do this using







simulate this circuit &ndash; Schematic created using CircuitLab