ferchup on "I can't change htaccess"

I know that. i try to explain with an example, to try to understand the problem. I know is weird:

1- Initial situation: I have this .htaccess with only read permissions:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

2- I change the permissions to be able to read and write the .htaccess.

3- I go to Permalinks ->Post Name and I press "Save changes". I check the .htaccess now and it has changed to this:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /vivepasionflamenca/
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /vivepasionflamenca/index.php [L]
</IfModule>
# END WordPress

4- I press to other place in my dashboard. For example, I go to see the posts, or whatever. Then, I check the .htaccess and ¡surprise! It has changed and it is the same that in the step 1. I mean, with only read permissions and with this contain:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

5- Conclusion: I cannot change the .htaccess file or before, or after or inside the #BEGIN - #END.

It is the most strange thing I have seen in WordPress, but is real and it is happening in the hosting, in localhost, when I deactivate the plugins or when I change the theme to twenty sixteen.

¿?