The brown spots appear to be sunburn.

Was the plant recently moved and potentially exposed to freezing temperatures or near freezing temperatures and/or wind for a short period of time. Where are you located? IF it was recently purchased and you are in a cold climate this could be a move from the store to your car etc. If a recent purchase the damage could have actually occurred before you bought it but the damaged tissues are browning now. As fawnridge said it could be sunburn too if the plant was growing in dim conditions and recently moved to a sunny window. This does not mean too much sun it means a change to more sun than it is used to which would have to be done gradually. A little more back history on this plant, how long you have had it and how you are growing it wil lhelp with diagnosis. Whatever the cause if it is in good conditons NOW new growth should be fine.

I have had the plant for just over 1/2 a year and originally it didn't have the browning patches and didn't have droopy leaves. I water it when the soil is dry and have pebbles at the bottom of the pot to try and help with humidity. I have moved it between houses once so it would be been outside briefly then or would it have suffered trauma from moving? Is there any techniques you suggest or anything else you need to know?

Once again where are you located (e.g. what state..............Minnesota and Southern Florida are very different, especially right now). It was taken outside.....recently (winter) in below freezing weather? IF so that could have caused those brown patches. Another thing is what type of heat do you have? If it is forced air and blowing directly on the plant that could also cause that browning. Less related to the browning (though maybe drooping) what type of soil do you have it in? Does the pot have a drainage hole? It looks like it may be draining into a second pot which could fill up with water. Soil should be moist but loose and well aerated (it can dry between watering). I like to loosen commercial potting soil with some extra perlite and orchid soil mixed in (or even pine mulch).

I'm actually from the UK in London so rarely ever below freezing temp! (Didn't realise this was a US website, apologies). I haven't repotted since buying the plant so that may be a factor that I need to change the soil but it does have drainage holes and the pot is rested on pebbles so hopefully not sitting in the water. No forced air is blowing onto the plant, the radiator is the other side of the room.

Nope not an USA site, plenty of UK folks here I was just making assumptions and thinking winter since I am in the middle of it right now LOL! Those big brown spots on the leaves still seem to indicate damage of some sort from sun, forced air, freezing (of course that one is probably eliminated). Pull the plant out of the pot an check the roots too.............should be some nice healthy white roots. If the roots are sparse and brown there could be other issues with soil and watering. BTW the plant does not look too bad, and they are pretty forgiving, but of course we are trying to improve on things and make it look better!

BTW with your closeups it looks like the plant has a nice base with a couple nice roots going into the soil. I would still guess that those brown patches on leaves and new growth are from something that happened in a short time period (once again dry air or sunburn or ?) that damaged those leaves. The soil does look fine and heavy for a Monstera, but IF there are good roots you could probably wait until Spring/early summer to repot. IF there is a problem (rotting roots or sour smelling soil) I would repot now.

Thank you for your help! Sorry I haven't got back to you sooner, I just had a good at trying to get the roots out but couldn't really manage, I did see some white roots and the soil smells earthy and not eggy! How should I be watering it and when I do repot in spring what kinda soil should I use? / should I be using fertiliser? I would love a heathy Monstera with healthy new leaf growth!

Good! In the wild these guys grow up trees and root into pockets of soil that are generally moist but very "airy" from the accumulation of decaying bark, leaves etc. I like regular potting mix but adding some compost, extray perlite, and some bark (you can use commercial orchid potting mix for the bark) The resulting soil will stay lightly moist easily without getting compact and waterlogged). Usually when you first repot there is enough nutrients in the soil initially. In a couple weeks when you see new growth you can start fertilizign regularly, especially through the summer months when the plant is actively growing. I slow down or stop fertilizer in witner.

Sorry for off topic. Is there a way to PM you woodnative? Thanks

rockdale sure. Not sure how to turn on or link my e mail to Houszz profile. You can send to the 3 names (together) Olga Chris Emily (at symbol) msn dot com.

Hi, Woodnative:

Sorry did not check back earlier. I am able to send you message through Houzz. I also sent the same message to your email so that you can have my email address. Sorry did not mean to make you post your email address out - you can edit it out in your last post.

Thanks

-rockdale

Thank you for all your help woodnative! How do you advise watering the plants? I have read some posts about doing it in the shower

You don't have to water them in the shower LOL. I mean if it is convenient to do so it is fine, but you have to lug the plants into the shower, soak them well and then let them dry off so they don't drip all over your floors. I just pour water onto the soil surface when needed......wetting the entire surface and until it starts to drain through. How often will depend on conditions (humidity, temperature, how root bound the plant is, how big the plant is, etc.). I generally try to water in the morning so any excess is gone before evening....probably not as important for the Monstera but good practice with some succulents and plants that could rot easily if water sits on the stems too long. An occasional shower, or placed outside in a gentle warm rain, will keep dust off the broad leaves.