which model you are using? Is it possible to share the configuration?
You can change the ip address of the interface from CLI like below :
delete interfaces <interface name> unit 0 family inet address 192.168.1.1/24
set interfaces <interface name> unit 0 family inet address 10.10.10.10/24
Enabling J-web:
set system services web-management http interface <interface name>
set system services web-management https system-generated-certificate interface <interface-name>
If the interface is not fxp0 interface and revenue interface (like ge-0/0/0) used for management , that interface should be configured to a zone and http/https should be enabled in host-inbound-traffic.
Eg:-
set security zones security-zone TRUST host-inbound-traffic system-services http
set security zones security-zone TRUST host-inbound-traffic system-services https
set security zones security-zone TRUST interfaces ge-0/0/0.0