[Plugin: Easy Table] Bold formatting doesn't work

use attr style on each cell.

[table caption="Just test table"]
no,head1,head2,head3
1,row1col1,row1col2,row1col3
2[attr style="font-weight:bold"],row2col1[attr style="font-weight:bold"],row2col2[attr style="font-weight:bold"],row2col3[attr style="font-weight:bold"]
[/table]

it may looks messy.
alternatively, use CSS for styling.
add this to the end of style.css on your WordPress theme directory.

table.easy-table tr:nth-child(3) {
   font-weight:bold;
}

note:
nth-child(3) is for third row.
if you want to bold every odd row use nth-child(odd).

table.easy-table tr:nth-child(odd) {
   font-weight:bold;
}