/etc/security/limits.conf not applied

I have /etc/security/limits.conf, that seems not been applied: a soft nofile 1048576 # default: 1024 a hard nofile 2097152 a soft noproc 262144 # default 128039 a hard noproc 524288 Where a is my username, when I run ulimit -Hn and ulimit -Sn, it shows: 4096 1024 There's only one other file in the /etc/security/limits.d that the content is: scylla - core unlimited scylla - memlock unlimited scylla - nofile 200000 scylla - as unlimited scylla - nproc 8096 I tried also append those values to /etc/security/limits.conf then restarting, and do this: echo ' session required pam_limits.so ' | sudo tee -a /etc/pam.d/common-session but it didn't work. My OS is Ubuntu 17.04.