To move or adjust notes horizontally

click it, open Inspector (F8) set the offset
https://musescore.org/en/handbook/inspector-and-object-properties#note

To be perfectly clear, what Shoichi mentions moves the notes/chord only visually.
To change the actual beat-position of notes, the general way is to use cut-and-paste. There are some shortcuts that only work if two adjacent notes/rests have the exact same duration, but no generic shift-contents command.

To perhaps clarify a little further:

In general, it should not normally be necessary to move a note left or right - the default spacing produced by MuseScore should be correct the vast majority of the time. The Inspector can indeed be used for those unusual specific situations where it is necessary to override this (e.g., cases involving three or more simultaneous voices on the same staff). But it's probably best to attach here your score here before resorting to this, to make sure there isn't some other misunderstanding about how this all works.

And as mentioned, if you actually mean you want to move a note not just horizontally in space on the page but actually move it to a different beat in time, then cut & paste is the quick and simple way to do this. This works beautifully not just for a single note, but for multiple notes at once or indeed passages of any length across any number of staves.