Just a guess here but I would say the strings you had before might have been medium gauge.
if the strings are too thin at the nutt they will vibrate at the loose space.
For a short term solution ( if you do not want to get rid of your new strings) you can loosen the strings off and put under the string at the groove a small folded piece of paper. This is fairly easy to do but try and not have the paper too big going near the first fret, try have any spare loose bit nearer the tuning keys.
if you still have your old strings you can take them to a shop and ask them what gauge they are. If not then take your guitar down and ask them if this possible. If not possible just get medium strings next and see what they are like.
And welcome to chordie
Ken
ye get some that are cut out for the job and others just get by from pretending