New MTB makes it feel like too much weight on arms? How do I make it better? My 10 year old montain mountain bike has quite an upright seating position and front tyre, which is what I think makes it very comfortable to ride for long periods of times.
Having recently bought a new mountain bike, with modern geometry and ridden several of my friends new mountain bikes with modern geometry as well, I noticed they all feel the same.  Wide handle bars, where you lean more forward when riding and it feels like there is slightly too much weight on your arms, which over time makes it them much more uncomfortable to ride than my old mountain bike.
I'm not sure what it is about these new MTB's but I am trying to figure out what I need to adjust to make my new MTB more comfortable.
How do I reduce the effect of too much weight on my arms? Seat up / down? Back / forward? etc.
EDIT: My new bike is size Medium and this is the geomtry table:

I normally try to keep the saddle as high as possible and I'm 5ft 10 tall.  My old bike has 26 inch tyres and this new one has 29's.
What I can tell you is limited without knowing further details like the model of both the new and old bike. But, looking at the geometry chart, seems like the new bike is most likely an XC/backcountry bike. The geometry on XC bikes is optimized for going fast on flat and uphill, so the stems are longer. However this bike seems to be halfway between a trail bike and an XC bike, as it has 120mm of travel and has a slacker headtube angle than most XC bikes.
So, without being able to look at your old bike to figure out what it was that made you more comfortable, my best guess is that you are used to a shorter stem. Try switching to a smaller stem, but make sure you also get wider bars or the steering will become very awkward. The longer the stem, the skinnier the bars should be and vice versa. Also, as stated in the comments, the bike may just take some getting used to. When I made the switch from XC geometry bikes to trail bikes, for a few weeks it felt like everything was off. But now I'm used to it.
I hope this helps. It's the best I can do without seeing both bikes.