Do not select by swiping. There should be no blue highlighted area, as that serves another function. (Right-click the blue area for options.)
Select by clicking the clips, as noted above.
If necessary, and it usually isn't, right-click a selected clip and GROUP SELECTED CLIPS.
If audio and video are linked, they will both move in unison, unless first unlinked via the right-click menu on either their video or audio track.
To deselect a specific clip, hold <ctrl> and click that clip.
For protection, Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar.