Problem loading CSS Sass file

I'm facing a problem where when generating the CSS file, where it is generated by a task made through Gulp. When interpreting Sass and generating CSS, the file in the site only changes if I delete and create a new .css file, otherwise it remains the same without the changes I made.

In hand-created CSS files, changes are made.

Something like a cache, but only for those made from Sass.

I have already changed the filename and continue with this "cache".

Thanks for the help.

Follow my gulpfile

''use strict';

var gulp = require('gulp');
var sass = require('gulp-sass');

var sassOptions = {
errLogToConsole: true,
outputStyle: 'expanded'
};

gulp.task('sass', function() {
return gulp.src('./assets/sass/**/*.scss')
.pipe(sass(sassOptions).on('error', sass.logError))
.pipe(gulp.dest('./css/'));
});

//Watch task
gulp.task('default',function() {
gulp.watch('assets/sass/**/*.scss',['sass']);
});'