The term "fixed" in custom ROM development usually refers to resolving common bugs found in early builds. For the A37m, these ROMs generally have the following "fixed":
Yes. Stock ColorOS uses 5GB for system. A fixed LineageOS 14.1 uses only 1.8GB, leaving over 6GB free for apps. oppo a37m custom rom fixed
Power off your phone, then hold Volume Down + Power simultaneously. The term "fixed" in custom ROM development usually