Hi,
Our supporter has checked your issues:
1. About the Multi currencies: You have to pay fee for using full function of this plugin, because you are using the free version so you only can add it to widget (https://prnt.sc/sx3YbKLM3btU). Our advice is: You may find another plugin or using paid version of Multi currencies plugin then the WPML's author will support you. Then if you face any issue you can ask help from them or ask help from internet: https://www.youtube.com/watch?v=J5Ld1BMmSJA
2. About the Email: We can not follow your instruction to help you with this issue. You may send the screenshot to SECRET INFORMATION box, If you still can not take a screenshot or video, then we can not help you in this case.
3. You have to publish the menu to use it: https://prnt.sc/xto4nkqYnntU
4. About the slider: If you want to setting the slider's image in mobile mode you can edit the setting: https://prnt.sc/7wPQnDgpDSib
The text's setting is in default mode. You can turn off the auto resize mode (https://prnt.sc/eQdgxyjOQ9iK) and use manual setting mode, you may find the instruction on Internet or reference our theme https://prnt.sc/At-QYHNr4kYC
If you do not know how to set up parameters such as: font text, color, background, image, position, responsive, ...then you may use these existing slider.
5. About the filter for prices: You are setting only for price text, not the value yet: https://prnt.sc/Nad-kWNcO24d
Regards,