can't reset MySQL root password

[Steve Doig]

I (thought I) have set a password for the root mysql user (to "password") on a Linux Mint localhost.

However, @ localhost/phpmyadmin, when I log in as root with that password, I receive the error:

#1698 - Access denied for user 'root'@'localhost'

If I run the command mysqld_safe --skip-grant-tables --skip-networking & I receive the error:

insight@insight-virtual-machine:~$ 2019-04-10T01:26:45.441033Z mysqld_safe Logging to syslog.
2019-04-10T01:26:45.444959Z mysqld_safe Logging to '/var/log/mysql/error.log'.
/usr/bin/mysqld_safe: 152: /usr/bin/mysqld_safe: cannot create /var/log/mysql/error.log: Permission denied
2019-04-10T01:26:45.448902Z mysqld_safe Directory '/var/run/mysqld' for UNIX socket file don't exists.
/usr/bin/mysqld_safe: 152: /usr/bin/mysqld_safe: cannot create /var/log/mysql/error.log: Permission denied
^C
[1]+ Exit 1 mysqld_safe --skip-grant-tables --skip-networking

I've run the command sudo chown -R mysql:mysql /var/log/mysql okay.

If I run the command mysqld_safe --skip-grant-tables & I receive error

insight@insight-virtual-machine:~$ 2019-04-10T01:37:13.592566Z mysqld_safe Logging to syslog.
/usr/bin/mysqld_safe: 647: /usr/bin/mysqld_safe: cannot create /var/log/mysql/error.log: Permission denied
Logging to '/var/log/mysql/error.log'.
2019-04-10T01:37:13.596242Z mysqld_safe Directory '/var/run/mysqld' for UNIX socket file don't exists.
/usr/bin/mysqld_safe: 152: /usr/bin/mysqld_safe: cannot create /var/log/mysql/error

Help appreciated.