There’s a chip on one of the props on my mini 3 so i got the screwdriver out and spare prop by
Make sure you’re using either the screwdriver provided by DJI or a JIS screwdriver NOT a Phillips/Posidrive one - there is a slight difference which means the JIS one is a lot less likely to strip the screw. 
The screws are supplied with lockinng compound applied, so you need to break the hold that has on the thread, so can be quite stiff to get started.
Been using the dji screwdriver it simply wont move lol
You could try a bit of gentle heat from hairdryer ?
Just don’t hold it to close or in the same area for to long, it may soften the thread lock a bit,
If you strip the top of the screw trying there is always a plan B.
Hopefully not
Ive done the exact same thing today to my 3 for the exact same reason. Is yours front right?
I grip the circular part that holds the screws to get the required force.
Had a similar experience on one screw last time I changed them all, just perservered in the end. Have you wiggled both ways to try and free it?
I sympathise as I had the same problem on my Mini 3. The problem is the DJI screwdriver provided - it’s the wrong size. I bought a screwdriver from Amazon that works perfectly as it fits thecscrew head snuggly and allows you to use as much force as you need without stripping the head. I’ve used mine several times to change props and it works perfectly. Amazon sell them and here’s the link: Wera 1550 PH Kraftform Micro ESD Screwdriver for electricians, PH 000 x 40 mm, 05030117001, Black/Yellow : Amazon.co.uk: DIY & Tools
Thanks just ordered from amazon
its rear right fir me lol
Too true. The supplied screwdriver is useless, Mine, the shaft turned inside the handle as soon as any force was applied. I got this
They are very TIGHT and secured with threadlock of some kind, so quite considerable (well controlled) force is needed. As indicated above, support the motor firmly.
In case it is ever useful, you can use Mini 3 Pro or Mini 4 Pro prop blades (which are identical), but you will need to keep the Mini 3 screws as they are different.
Holding the tip of a soldering iron on the screw head for 30 secs should soften the threadlock sufficiently to move the screw
Note what @MartG1960 has pointed out above, the screws the props are secured with they are Japanese standard. (JIS).
Update i got the correct screwdriver and replaced the props easily. Thanks for all the advice everyone.
Really interested in this image. Why?
Mini3 and Mini 3 pro - what the main difference / marketing?
You can find all the specs for the Minis on the DJI website.
Basically, the more you pay, the more features you get:
Mini 3 has only downard anti-collision sensing, 3 Pro adds front & rear, 4 Pro has all-round. (I suggest gettingthe highest spec you can afford.)
https://ww.dji.com/uk/products/camera-drones#mini-series
(3 Pro is not currently listed on the main page, so may be out of production, but probably some still in the shops and some going secondhand.)
The blades for the Mini 3, 3 Pro & 4 Pro are identical, but they are sold with the screws appropriate to the motor on the drone. Blade packs will be marked for each drone, but only the screws are different.
Weight saving. 
