Using Sibelius 7 how do I resolve overlapping notes so both parts can be read. For example in a two stave score for SATB, sopranos have a dotted minim and one crotchet in a bar, altos have four crotchets but the first note for soprano and alto in the bar is the same note so the first alto crotchet note in part 2 totally hides the soprano dotted minim in part 1. I cannot find a way of moving one of the notes slightly so both can be seen.
I take it you mean something similar to the first beat in the bass in the second measure of this example. This is in Sibelius 4, but I don't think Sib 7 works much differently: the tenor is in Voice 1 and the bass is in voice 2, and this is the default spacing, i.e., automatically without collision.
If you are using voices 1 and 2 already, you might want to look at things like whether the layout is locked, and whether extra space is being allowed for colliding notes in the note spacing rules - I know that these settings have carried over into recent versions.
Failing that, check the X coordinates of the notes in Inspector. The spacing in my example is automatic, so the notes show 0 displacement in the X coordinate. If the spacing in yours with the collision is 0 as well (which would be strange), then your final resort would be to move the dotted minim right (an X value of 2.25 usually works for me). My own experience, however, is that when the notes collide like that, either you are using the wrong voices (say, 1 and 4 rather than 1 and 2) or there is a non-zero value in the X coordinate of one of the notes (usually left over from earlier edits).