Arduino motor shield has weak power

I have an easy setup, an Arduino motor shield attached to an regular arduino and I have attached a simple DC motor on channel B. I have found some code for using it but the force behind the DC motor is weaker than when I just attach it to a regular pin or to the 3.3 or 5 volt. The point is that it is that little bit of extra force that I need for my project to work. I have found the code for the brakes and I can control the speed and the direction of the motor, but I can't figure out how I can give the motor more power.
I wondered if it was possible to do so and if so, how it should be done.
I hope to find my answer here.

There are multiple "motor shields" so a link to the exact same one you are using is vital.

Most shields have an option for external power and that may involve a jumper or a track cut.

Running a motor directly from an Arduino is never really recommended.

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It will help you get the best out of the forum in the future.
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Yeah, I'm sorry it's my firts time on here so I didn't knew how it worked.
It's in fact the official motor shield of Arduino. But even on the site I couldn't find examples. On a lot of examples on google and youtube they also put the DC motor right onto this shield. I have tried different types of motors but they all seem to have this problem.Arduino Motor Shield Rev3 | Arduino Official Store

(mod edit)

The basic instructions are very clear about needing to use an external supply for the shield.
The 298 also has a power loss associated with it too so any external supply also needs to account for that as well.

See the “documentation” section from the link you provided as it gives you both the reason you dont see much power and the fix.

Ok thank you, I must have missed that part