To change string from all file:
awk -i inplace '{gsub("keystring","newstring",$0); print $0}' *.html
awk -i inplace '{gsub("keystring","newstring",$0); print $0}' */*.html
awk -i inplace '{gsub("keystring","newstring",$0); print $0}' */*/*.html
- BTC
bc1q0qhgw5pdys7qqw07rcsyudu5wmv6208nhp5xtn
- ETH
0x8cdc24eeb9d1bf46929b2106e3535e0d1953fe1b
USDT (TRC20)TGW1c7hzyszQNhQHM3aGa1nEKDNuyPueNE