Permalink Post name url option trails with '/index.php/sample-post/'

Hi all,
Just beginning learning WordPress. I’ve set up a test domain on my hosting server. I would like the Post name option in permalinks to be ‘http://thisisatest.ie/sample-post/’ instead of the option it is giving me
‘http://thisisatest.ie/index.php/sample-post/’
I also tried to add the custom structure as http://thisisatest.ie/index.php/%postname%/ but when I navigate to the about page for example, I receive the error ‘The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.’

Thanks in advance, any help is appreciated.