Series connect it within the line of the circuit for which you are interested in measuring the current flow.
More detail
Since we measure the flow of current IN the circuit, the ammeter must be connected in series with the part of the circuit for which you are interested in measuring the current flow.
One of the ammeter's terminals must be connected to a point of the incoming current flow and its second terminal must be connected to the point of on-going current flow. To do this, cut the relevant circuit wire and connect one terminal of the ammeter to each end of the cut.
Ammeter is coneccted in series with circuit but Voltmeter is connected in parallel.
The ammeter does affect the flow of current in a circuit, however, the resistance of the ammeter is so small in comparison to the circuit that the effect is negligible. It is connected in series.
To measure the current in the circuit an ammeter is used and it is connected in series
The positive terminal of the battery would be connected to the positive terminal of the ammeter. The load would then be connected between the two negative terminals, positive side of the load being connected to the negative side of the ammeter.
measures current in a circuit, must be series connected