I use set default IP and MQTT as follows:
Edit file ESPEasy.ino and paste on line 84
#define DEFAULT_USE_STATIC_IP false // true or false enabled or disabled set static IP
#define DEFAULT_IP "192.168.0.9" // Enter your IP address
#define DEFAULT_DNS "192.168.0.1" // Enter your DNS
#define DEFAULT_GW "192.168.0.1" // Enter your gateway
#define DEFAULT_SUBNET "255.255.255.0" // Enter your subnet
#define DEFAULT_MQTT_TEMPLATE false // true or false enabled or disabled set mqqt sub and pub
#define DEFAULT_MQTT_PUB "sensors/esp/%sysname%/%tskname%/%valname%" // Enter your pub
#define DEFAULT_MQTT_SUB "sensors/esp/%sysname%/#" // Enter your sub
And edit file Misc.ino and paste on line 844
#if DEFAULT_USE_STATIC_IP
str2ip((char*)DEFAULT_IP, Settings.IP);
str2ip((char*)DEFAULT_DNS, Settings.DNS);
str2ip((char*)DEFAULT_GW, Settings.Gateway);
str2ip((char*)DEFAULT_SUBNET, Settings.Subnet);
#endif
#if DEFAULT_MQTT_TEMPLATE
strcpy_P(Settings.MQTTsubscribe, PSTR(DEFAULT_MQTT_SUB));
strcpy_P(Settings.MQTTpublish, PSTR(DEFAULT_MQTT_PUB));
#endif
