The engine burns would be used to change the orbital altitude. That would change the period of its orbit and that would adjust its track over the earth. It's not unusual for military satellites to adopt special purpose orbits (for example, crossing the same place on the earth at the same time every three days), and OTV 1-1 has been shifting between such synchronized orbits.

It's very expensive in terms of fuel (that is, virtually impossible) to make any extensive out-of-plane maneuver, but a lot can be done by varying altitude. The amateurs who have been tracking OTV 1-1 have 'lost' it a few times when it has adjusted its orbit, usually because the observing weather has not been favorable for a few days and any slight orbital change has had time to accumulate.

It's about +3.5 average (2.2 - 4.5) magnitude. It's orbital inclination is 40 degrees making it visible in the twilight sky when conditions are right anywhere between about 45N and 45S latitudes. It's orbital altitude is getting lower and it is maneuvering, both of which make predictions of where to look less precise, but http://www.heavens-above.com has predictions. It travels west to east.