Beginer Guitar tab transcription. Treble semiquavers not aligning with bass crotchets.

Hi I'm new again to musescore and trying to transcribe an audio file I have to guitar tab in the tuning DADGAD for guitar. Every time I add a semiquaver directly above a quarter note it offsets itself in front of the quarter note instead of being synchronized.

The first picture is with the unlocked treble note slotted in above the bass note. The second picture shows after I have clicked it in and it it has been placed in front of the bass note offsetting it.

Any help would be muchly appreciated.